Jean-Louis Flandrin's A Time to Embrace

While this study considers the effects of religious rules on fertility in a specifically Jewish context, it is strongly influenced by the late French historian Jean-Louis Flandrin, whose 1983 book A Time to Embrace addresses this issue in a Christian context.Footnote ¹⁰ One of the central questions in Flandrin's book is similar to the one raised here. Flandrin wanted to know whether medieval ecclesiastical rules regarding marital sexuality, such as prohibitions pertaining to sexual relations on certain days, impacted medieval women's reproduction. In the period analyzed by Flandrin, between the sixth and the eleventh centuries, a large number of so-called “penitentials,” or “books of penitence,”Footnote ¹¹ were common on the European continent and on what we call today the British Isles. These books were intended for confessors. Using them, a confessor could learn what he should ask a penitent during confession and what appropriate expiatory act he should then prescribe. Many different issues are dealt with in these books, but Flandrin is concerned only with questions of sexuality between husbands and wives. On this subject, the instructions in these books sound often like this: “Did you unite with your wife during her menstruation / on a Sunday / while she was pregnant / in a non-natural way? If you did, your punishment is seven days without meat / ten days of cold baths / six months of weekly fasts.”Footnote ¹² Even a superficial reading of the penitentials gives the impression that on many days of the year, sexual intercourse between a husband and wife was considered sinful: Flandrin's inquiry seems therefore to be well justified.

In his study, Flandrin uses a great number of penitentials and employs modern knowledge about the female fertility cycle as well as sophisticated mathematical models to estimate the fertility of medieval women and the implications of various levels of observing these religious regulations. Finally, he reaches two conclusions. The first one is that the vast majority of the prohibitions that were related to the biological cycle of the woman—such as prohibitions against having intercourse during pregnancy, during menstruation, and for some time after delivery—had very little impact, if any, on women's rates of reproduction, since they referred to periods in which women's chances of becoming pregnant were slim at best. Flandrin's second conclusion is that calendar-based prohibitions, such as prohibition of sexual relations on certain days or seasons, could have had an impact on fecundity. Those lasting several consecutive days and at times many weeks, such as those related to Advent or Lent, or to additional periods that were marked in the medieval Christian world, could have been very significant: they were likely to cause a woman to lose opportunities to conceive, if ovulation occurred during the prohibited time.

Based on the data he gathered from his sources, Flandrin reaches one fundamental conclusion. Not only can it be assumed that some of the prohibitions caused a decline in the birth rate among Christians who observed them, but if these prohibitions had been adhered to meticulously, and in large areas, the very existence of Western European culture would have been risked as a result. Luckily for European Christianity, the clergy's demands were one thing, and the actual sexual behavior of the laity in general was quite another.

Medieval Jewish Regulations of Marital Sexuality

Limits regarding the days on which a married couple could have sexual relations have a history also among Jews. Unlike the situation in large parts of the Christian world, this is not only a matter of the past: these limits still exist among Jews who observe, more or less strictly, rabbinic law. The number of those who observe these laws is often estimated to be between 10 and 20 percent of world Jewry today. Can a study similar to the one performed by Flandrin, but applied to the Jewish world, be useful?

Flandrin found that the majority of the Christian prohibitions were related to the days of the week and to the liturgical calendar. Only a few depended on the woman's biological cycle. In the Jewish world, the situation is exactly reversed. The majority of the prohibited days for intercourse are directly related to feminine biology. The Jewish calendar contains very few days in which marital relations are categorically prohibited. Two of them originate in talmudic law: Yom Kippur (Day of Atonement, the holiest day of the year)Footnote ¹³ and the ninth day of the month of Av, a fast commemorating the destruction of the temples.Footnote ¹⁴ The other prohibited days are of a much later origin and depend on local or group (e.g., kabbalistic, Hasidic) traditions: Christmas night, or as it is often called in Jewish sources, the “Nittel”;Footnote ¹⁵ the first (and some also say the last) night of Passover; the holiday of Shavuot,Footnote ¹⁶ the Jewish counterpart (or, to an extent, origin) of Pentecost; the Jewish New Year; and a few other dates.

It is obvious that the impact of not having relations on these few days of the year is, on the whole, negligible, even if it might influence the chances of a specific woman at a specific time to conceive. Having said that, we should remember the existence of two additional rabbinic practices that connect sexuality to the weekly cycle: a custom of not having relations on Saturday, Sunday, Monday, and Tuesday, and another custom of having marital relations specifically on Friday night (a night also referred to in this article as “Sabbath Eve”). These two practices are found in the talmudic period (around the third to sixth centuries c.e.)Footnote ¹⁷ and continue to be attested, although in very different frequency, in later generations. The first custom seems to be, at best, a marginal curiosity. We will mention it again later but will remain skeptical about the possibility that it ever had many followers. The second one is much more commonly attested; however, it is not always clear whether this meant couples refrained (or were encouraged to refrain) from relations on other days of the week, making Friday their exclusive day for intimate relations. The prescription may have led some couples to have more frequent relations on Fridays without necessarily refraining from relations on other days of the week as well. With regard to our issue, the difference between these two options might be significant. Nevertheless, we will assume for now that even observant couples did not refrain from having relations on other days of the week; therefore, this “Friday rule” is negligible for our concerns. Later, we will raise the issue again, and consider what its implications might have been for couples who engaged in marital relations almost exclusively on Sabbath Eve.

Considering all of the above, it seems that in order to understand the implications of traditional rabbinic laws on the reproduction rates of Jewish women who observe them, one should focus on biology-related prohibitions, not on calendar-related ones. But if this is the case, are we not simply wasting our time? Did not we learn from Flandrin that such prohibitions have only a minor effect on fecundity, because the prohibited days are almost always infertile ones anyway?

In order to answer this question, we must ask whether Flandrin's findings are relevant to the Jewish world. And for this, we have to consider the issue of niddah and the way it is integrated with women's fertility cycles.

Niddah

The term niddah is used in Jewish tradition with regard to menstruation: it implies “a menstruating woman,” “menstruation,” “laws related to menstruation,” etc. The root of the term means “wandering” or “exclusion” and is most certainly related to the exclusion of the menstruating woman from various social activities. The Jewish laws of niddah, like many Jewish laws, are based on biblical laws but are, at the same time, very different from them. Three biblical texts on the issue from Leviticus (15:19–24, 18:19, 20:18) are particularly crucial to understanding these laws. According to these texts (assuming all of these laws are considered complementary), sexual relations are forbidden for seven days after the appearance of menstrual bleeding. During this time the woman (and, if they have relations, her partner as well) is impure; the punishment, if this prohibition is transgressed, is severe.Footnote ¹⁸

Obviously, Jewish law did not stop with the Bible but continued to develop. In the talmudic period, the length of prohibited time was extended. This extension became part of the halakhah, the Jewish legal system, to this day and combined what seem to be, in the Bible, two different types of bleeding: a “regular” type (menstruation) and an extended one.Footnote ¹⁹ It has been claimed in the rabbinic literature that it was women who decided to act more severely and make the prohibited period longer.Footnote ²⁰ According to this law, the period of seven days was considered to begin only after the end of the blood flow. These days were now called “the seven clean/white days” (in English, one can also find the expression “seven days of cleanliness”). It was mandated that during these seven days, the woman must make sure, by frequently checking herself, that she is not bleeding. Only after the cessation of the bleeding, and the additional seven days, can the woman be considered ready to enter a state of purity. Thus, since the time of bleeding is generally four to six days, the entire prohibited period became approximately eleven to thirteen days for most women. The talmudic literature also made a ritual bath an obligatory step at the end of that time, without which the woman remains impure. This is not the case in the Bible, where a ritual bath seems to have been prescribed only for women who have long and extensive bleeding, not for women who have a normal menstrual flow.Footnote ²¹

During the Middle Ages another rule, based on talmudic concepts, came into being and was universally accepted around the sixteenth century: if a woman engaged in sexual relations immediately prior to the beginning of her period (and according to some, even if she did not), the bleeding period was decided to be, regardless of its actual length, no less than five days—or, according to Spanish and North African (“Sephardic”) Jewish codifiers, four days. The reason behind this practice is related to the fact that much of the sperm ejaculated in a woman's vagina is expelled minutes, or hours, or days after intercourse. According to talmudic law, this release of sperm may render the woman a subject of another type of impurity, which can invalidate her counting of the “seven clean days.”Footnote ²² The impact of this rule is that a woman cannot be considered impure for less than twelve days (5+7)—or eleven days, if she follows the Sephardic custom of 4+7—from the onset of her period. For Jews observing Jewish law in its Orthodox form, this is still the law to be followed today.Footnote ²³ Obviously, for many women who experience a bleeding period that is longer than four or five days—and current studies show that this is not rarely the caseFootnote ²⁴—the actual time of being in the halakhic status of niddah might be longer than this minimum of eleven or twelve days.

One should remember that the number of days inappropriate for sex in each cycle is based upon an assumption that the woman performs the ritual bath immediately at the end of the prohibited period, in the evening that ends the “seven clean days.” If the bath is delayed, the woman remains impure. Thus, the prohibited period for sexual relations will be longer. The same will happen if the woman experiences various types of spotting during the seven clean days; in some cases, the counting will even have to start all over again.

The Menstrual Cycle

The Jewish laws we have discussed so far are obviously related to a biological cycle. Before we move forward, a quick refresher on this cycle might be appropriate.

Key factors in the regulation of the cycle are the follicles, the protective shells of the eggs that grow in the ovaries during the first half of the menstrual cycle (“follicular phase”). Their growth is triggered by follicle-stimulating hormone, which arrives from the pituitary gland after it receives hormonal signals (gonadotropin-releasing factor) from the hypothalamus. When the follicles grow, they produce increasing levels of estrogen. Once the estrogen produced by the growing follicles reaches a certain level, it triggers the pituitary gland to release a surge of luteinizing hormone. The luteinizing hormone causes the most mature follicle to burst open and release its egg into the fallopian tube: this is ovulation.

The time surrounding ovulation is, as is well known today (but was not known until the 1930s), the most apt for conception. Nevertheless, because the released egg can survive in the woman's body for twelve to twenty-four hours, relations that occur until about a day after ovulation might still lead to conception. It is also possible that more than one egg may be released from the ovaries: in such a case, the window of fertility might extend even longer. But there is still another scenario that can extend the window of fertility: sperm cells can survive in a woman's body for several days; because of this, even if relations occur a few days before ovulation, there is still a chance of fertilization.

If the egg is not fertilized, the luteal, or post-ovulatory, phase begins. In about twelve to sixteen days after ovulation, the uterus will shed its lining, bleeding will occur, and a new cycle will begin. It is generally assumed in the medical literature that for many healthy women in the so-called “childbearing age” who have a cycle of about twenty-eight days, the middle of the cycle (more or less from the twelfth to the sixteenth day) is the most plausible time for conception. This does not necessarily apply to all women, at all times. Significant variations are known, and some healthy women might ovulate earlier or later.Footnote ²⁵ Certainly, this does not mean that a woman is equally fertile at all times within this long period: it only means that a short window of fertility of about twenty-four hours occurs during this time frame, and that sexual relations performed during or shortly before this window may lead to conception. If a woman wants to become pregnant, she should try to catch this window by having relations between days twelve and sixteen. If she wants to avoid pregnancy, and she is not using a more efficient contraceptive method, it is better if she avoids relations during these days; or, for those without access to modern tests that indicate the exact timing of ovulation, a still more cautious approach would be to avoid sexual relations between days nine and eighteen. Sex outside the wide range of days nine to eighteen is less likely to lead to conception, although conception might still occur if ovulation is very early, very late, or in rare cases, if a second ovulation happens.

Niddah Laws and Fertility

Based on all of the above, one might suggest that the niddah laws increase human reproduction: couples who follow them are likely to avoid relations during the first twelve days of the cycle, and engage in them exactly when the woman is most fertile. To quote Rachel Biale in her Women and Jewish Law: “By virtue of the fact that purification and resumption of sex normally coincided with ovulation, the laws of Niddah favored procreation.”Footnote ²⁶ The same conclusion, but in a more scientific style, may be found in an article published in 1988 in the Journal of Biosocial Science. There, the author, Susan K. Gardin, concludes that since most Orthodox Jewish women complete the period of ritual impurity and supposedly attend the ritual bath on or before their ovulation, “the majority of cycles are potentially exposed to coital activity during a fertile period. . . . The increased likelihood of coitus following abstinence has potential fertility-enhancing effects.”Footnote ²⁷ These two statements—which are given here only as two well-formulated examples of a very common claimFootnote ²⁸—might be correct with regard to many women within certain scenarios of observance and practice. But they might not be so accurate with regard to many other women or when modes of observance and practice diverge from certain idealized scenarios.

The idea that the menstrual cycle lasts for twenty-eight days, and that ovulation happens exactly halfway through, is very helpful for calculations. The reality is that although some women indeed have a stable cycle of twenty-eight days, with ovulation occurring exactly in the middle of it, many women do not. Healthy women can have a cycle lasting from about twenty-two days to about thirty-six days and with the length varying from cycle to cycle.Footnote ²⁹ When one takes this into consideration, the calculations come out differently.

For women who keep niddah laws and who have an average-length cycle (around twenty-six to thirty days), there is indeed a good chance that they will resume sexual relations just around the time of ovulation (which is likely to occur at days twelve to sixteen). If these women want to become pregnant, keeping niddah laws might in fact push them towards having relations at a very apt moment.

For women with a long cycle (thirty to thirty-five days), there is a good chance that before they ovulate (which is likely to occur around days sixteen to nineteen), they will already have resumed sexual relations. If they continue to have relations during the days following their ritual bath, these relations may lead to conception.

Unlike the two groups above, for women with a short cycle (less than twenty-six days), there is a good chance that when ovulation occurs, around days nine to twelve, they will still be considered impure and will not be able to have sexual relations. If they plan on having children, this is a bad news: relations that occur after their ritual bath will simply be too late. If they keep the niddah laws meticulously, their chances of getting pregnant will be severely affected. If the length of their cycle fluctuates, and it is sometimes longer, they may eventually become pregnant, although they might have to wait a long time for their first pregnancy or have longer than wished-for intervals between pregnancies. If on the other hand their cycle is consistently short, their chances of ever becoming pregnant are very low.

The Situation Today

For decades already, the fertility challenges for women with a short cycle who observe niddah laws have been known to gynecologists treating these women and to the rabbis who work with them. A name was even invented for this man-made problem: “religious sterility.”Footnote ³⁰ The first substantial rabbinic discussion of this issue that I have found was composed in 1964. The author, the eminent halakhic jurist Shlomo Zalman Auerbach, prefaces his discussion by stating that this is only an attempt to deal with the issue, to be considered by other halakhic experts. He does not necessarily mean it as a practical ruling. At the same time, he acknowledges very clearly in his opening words:

Auerbach's solution is that women who suffer from such a condition should insert a special kind of rubber tube into their vaginas before the beginning of their period. The tube would be constructed in a way that would channel all menstrual blood directly out of the woman's body, without any contact between the blood and the vagina.Footnote ³² Using sophisticated halakhic logic, such a device would enable the woman, according to Auerbach, to bathe seven days after the beginning of her period and become available to her husband on the eighth day.

Was Auerbach's proposal not accepted because of technical difficulties or disagreement with other halakhic experts? I do not know. I was not able to find later discussions of Auerbach's suggestion.Footnote ³³

Some years after Auerbach's proposal, in 1970, the first scientific article on the matter that I have been able to locate was published, co-authored by biologist Bruno Lunenfeld along with a certain N. Birenbaum.Footnote ³⁴ It was introduced by an editorial note that hints that the issue was well known among halakhah experts: “This article . . . deals with an urgent and disturbing problem, as any expert of practical halakhah knows.”Footnote ³⁵

Ten years later, the first article in English on this matter of which I am aware appeared in a collection published in 1980.Footnote ³⁶ Both the articles from 1970 and 1980 were produced by and written for a learned Orthodox readership interested in sophisticated halakhic questions. They can also be considered as belonging to an important sub-genre of studies on the interfaces between medicine and Jewish law.

The first discussion of the same issue in secular medical literature appeared in a journal called Harefu'ah (Medicine), in 1970—the same year Lunenfeld and Birenbaum's article appeared.Footnote ³⁷ Its author, Shlomo Renzo Toaff, was a well-known Orthodox gynecologist who headed the maternity department of a hospital in Tel Aviv.Footnote ³⁸ Some years later, in 1976, a short summary of Lunenfeld and Birenbaum's previously mentioned article—which Lunenfeld also presented orally at a conference in 1976—appeared in a volume of Sefer Assia, an annual collection of medical articles.Footnote ³⁹ In 1981, another article by Lunenfeld on the matter was published in the Israeli equivalent of Scientific American, the journal Madda (Science),Footnote ⁴⁰ and in 1984 an article by Joseph Green touching on this very same problem appeared in the Hebrew medical journal Assia.Footnote ⁴¹

With these six articles published in religious and secular journals over the course of fourteen years, it is fair to say that this rather disturbing conflict between Jewish law and contemporary medical knowledge has been exposed for the world to see. Obviously, the “world” probably mostly means physicians and other laypeople interested in science who care to read such articles. I do not know when this issue became widely known to observant Orthodox women, the population to whom this information would have been particularly pertinent.

This problem is perhaps disturbing to some, but in the eyes of the authors who wrote these articles, it is not a serious one. The reason is that, together with describing the problem, they propose some reliable solutions, the main one being this or that protocol of treatment by hormones.Footnote ⁴²

In fact, in a certain halakhic mindset, if modifying Jewish law is too compli-cated, one should try instead to modify Jewish women.Footnote ⁴³ Each of the authors of these articles, themselves Orthodox men, did not even raise the possibility of a change in religious practice. This attitude still prevails in more recent years: doctors worldwide who treat Orthodox women (often these doctors are Orthodox themselves) prescribe hormones to these women.Footnote ⁴⁴ This is done in order to extend their cycle and guarantee that they do not ovulate before they can take their ritual bath. And it works. “These days, no woman remains childless because of the problem you mentioned,”Footnote ⁴⁵ wrote Rabbi Yossef Eitan, one of the advisers in an Orthodox institute in Jerusalem that specializes in fertility issues. This was his online answer to a woman who had written, some hours earlier, “I want to keep niddah laws, but my ovulation occurs between days ten and twelve, before the end of the ‘seven clean days.’”Footnote ⁴⁶ Probably, in most cases, this rabbi is right. The hormone-based solution works: these women's cycles are prolonged, and they are able to become pregnant.

Leaving aside the possible debate about the ethical justification of using hormones in such cases—to which those supporting this option would answer by saying that many women take, often for years and of their own will, contraceptive hormones, while those opposing it say this is a futile comparison between very different dosages and protocolsFootnote ⁴⁷—some questions still linger after reading this rabbi's answer, one of which is the following: What is the percentage of halakhah-observant women today who have difficulties in becoming pregnant simply because they ovulate during the halakhically prescribed niddah period?

Rabbi Dr. Mordechai Halperin, the head of the Schlesinger Institute for Medical-Halachic Research,Footnote ⁴⁸ located in the Orthodox-affiliated Shaare Zedek hospital in Jerusalem, affirmed in a personal communication that, based on his clinical experience but lacking hard data, he estimates that the combination of a short period, together with observance of niddah laws, is the reason for the conception difficulties of roughly 20 percent (with a possible deviation of 10 percent) of women who contact their clinic.Footnote ⁴⁹ Not unlike Eitan, quoted earlier, Halperin concluded his response by saying that this condition is one of the most easily correctible fertility problems he confronts. Obviously, an assertion “based on clinical experience but lacking hard data” is very problematic, but it seems Halperin's insights are, if not identical, at least somewhat close to those provided by other researchers and practitioners.

In fact, another Orthodox gynecologist, Dr. Daniel Rosenak, provided a similar figure in a 2006 interview in a religious newspaper.Footnote ⁵⁰ According to Rosenak, this seems to be the cause of inability to conceive in about one out of every four Orthodox women he checks for possible infertility. In other words, according to these two testimonies, for about one out of every four or five halakhah-observant women today in Israel who have difficulties becoming pregnant without medical assistance, the reason for the problem seems to be mostly related to their observance of the niddah laws rather than to any other medical-organic issue. The scientific study by Haimov-Kochman et al., published shortly before the final revision of this article, suggests a similar estimate: it finds that, among the infertile Orthodox women under study, the prevalence of precoital ovulation is 21 percent.Footnote ⁵¹ It should be noted that none of these studies or practicing gynecologists attempts to give an estimation of the total number of women affected by niddah-related infertility within the wider Orthodox community: they speak about one out of every four or five women they see for infertility issues.Footnote ⁵² It is very risky to try to estimate the percentage of women from the general population of observant Jewish women who are affected by this problem. As we will mention later, studies to determine this number are currently underway. Meanwhile, considering the fact that roughly 10 percent of women worldwide are considered to have some kind of infertility issues, and even if Orthodox women, who tend to marry young, might suffer less from such problems, it seems reasonable to guess that the number of those suffering in particular from “religious infertility” is somewhere between 1 and 4 percent. Of course, this estimate should be taken with a grain of salt until more solid numbers about the situation today are available.

In November 2006, a heated public debate on this issue erupted in Israel. It seems to have begun with an article already mentioned, presented as an interview in the National-Orthodox weekly newspaper Hatsofe and written by Ms. Rivkah Shim'on, an Orthodox woman who instructs brides about the laws of niddah prior to their wedding. The interviewee was Dr. Daniel Rosenak, the Orthodox male gynecologist we have just quoted.Footnote ⁵³ In this article, Shim'on and Rosenak artificially construct a format of questions (by Shim'on) and answers (by Rosenak), laying out Rosenak's arguments against the rabbinic practice of adding seven days to the actual period of bleeding and his call to return to the biblically sanctioned custom of seven days of niddah. Rosenak provides various arguments, including nationalist ones, why this is, in his opinion, a desideratum, as well as why he believes such a reform is halakhically feasible. For the sake of our discussion, only his arguments for a change due to the problem of the so-called “religious sterility” are relevant.Footnote ⁵⁴

Rosenak claims that, based on his experience, more than a quarter of the cases of infertility among observant women are the outcome of the observance of -niddah laws. He also hints, though very briefly, that this is not a new phenomenon, and that Jewish demography must have been affected by this problem: “Calculate by yourself,” he urges Shim'on: Since the rule of the “seven clean days” was enacted during the talmudic period, “we have lost millions of Jewish souls! They, and their descendants, and the descendants of their descendants.” Objecting to the idea that hormones are an appropriate solution, he acknowledges the fact that in the Orthodox world, of which he is part, the possibility that major rabbis will put his suggestion into practice is very unlikely; but for him, in any case, such a change should come from the grassroots. His goal, he argues, is not to convince rabbis but to make observant laymen and -women aware of the problem and its possible solutions.

Minutes after this article was published on the journal's website, reactions -started to appear online, some supporting it and some objecting to it. A few days later, substantial responses began to be published in the same journal and in -others, in print as well as online. Rosenak published several formal responses dealing with the points raised in the initial article and in articles criticizing it.Footnote ⁵⁵ The details of the debate have little importance for our topic: most of them concern the exact halakhic definition of the seven clean days and the (im)possibility of its modification, as well as the pastoral issues the debate raised. Some of those opposing Rosenak, generally not physicians themselves, argued that a treatment with hormones has no substantial risk, a point Rosenak refuted.

Among the many articles that have been published on the matter since then,Footnote ⁵⁶ one of the most comprehensive is by Tova Ganzel, a biblical scholar, and Deena Zimmerman, a pediatrician.Footnote ⁵⁷ They conducted their research under their role of “halakhah counselors” (yo'atsot halakhah), a rather new profession of Orthodox women who are trained to instruct other women in halakhic questions, often ones related to the niddah laws. One of these authors’ main theses is the suggestion that if women who are presumed to suffer from “halakhic infertility” would check their ovulation patterns and, at the same time, stick to permissible halakhic practices (such as bathing at the earliest allowed moment), the number of those who would still need hormonal treatment would be significantly lower than previously estimated.

Most of Ganzel and Zimmerman's work is based on the study of medical records from various clinics in Israel, in neighborhoods where the vast majority of the population are Orthodox Jews. In their own calculations, Ganzel and Zimmerman find that for about 35 percent of the women whose main reason for visiting the clinics is infertility, delaying ovulation might be helpful.Footnote ⁵⁸ In other words, they probably have “religious infertility.” And yet, in some other clinics, the percentage of those thought by the clinic personnel themselves to suffer from the same situation is significantly lower.Footnote ⁵⁹ These two authors also believe that many women delay their bath, perhaps more than they would if they had more precise medical and halakhic instruction. Thus, for example, they found that only about 14 percent of the Orthodox women who were treated for possible “religious infertility,” and whose records they studied, bathe normally on the twelfth day of their cycle. Most (about 70 percent) bathe later, on days thirteen through fifteen. The authors claim that a careful medical and halakhic analysis of these women's cycles would show that many of them are halakhically able to bathe earlier than they think and could thus enhance their chances of conception.

It is unnecessary for our purposes to go into the details of all their claims; suffice it to say, the main argument of Ganzel and Zimmerman might actually support our suspicion: many women, if they refrain from sexual relations during the first two weeks of their cycle due to their own understanding of their cycle and halakhic rules, might have problems conceiving. The sophisticated methods Ganzel and Zimmerman suggest for solving this problem are entirely dependent on a modern understanding of the menstrual cycle and of ovulation—and on a realization that for some women, every day and possibly every hour of delay might be crucial. Teams of experts can explain all this to women, but women who do not have this information cannot increase their chances of conceiving, either because they are unaware that an early bath is so important or because they do not know when they are most fertile.

Niddah Laws and Jewish Women's Fertility in Previous Generations

All the solutions suggested in the articles we mentioned are based, implicitly or explicitly, on four facts or assumptions:

1. 1. That the biology of the cycle is known to us through modern research, and that there are reliable methods for determining the moment of ovulation.

2. 2. That hormones can generally help in modifying the cycle, so that ovulation will occur later than it naturally would otherwise.

3. 3. That due to all this knowledge, any solution generally needs to be used for a well-defined time: only when the couple is actively trying to conceive.

4. 4. That the halakhically prescribed length of the niddah period can, for some women, end after twelve days (Ashkenazic custom), or eleven days (Sephardic custom).

Despite disagreement on various details and practical questions, most experts involved in the debate surrounding halakhic infertility seem to agree with the claim that “these days, this is not a problem.” Or better said: it is a problem to which reliable (although, according to Rosenak, still medically and ethically problematic) solutions exist. One can only hope that Orthodox women who have to deal nowadays with this issue will consult specialists and get appropriate help—whether they do it by revising their niddah practices, following halakhic experts; by seeking hormonal treatment; or by simply ignoring some of the halakhic rules is, obviously, not our concern.

But what happened in the past? Ovulation has been understood only since the 1930s, and efficient ways of affecting the menstrual cycle using hormones were not available before the 1950s and 1960s. Reliable methods that enable women to know the time of their ovulation (initially the Basal Body Temperature method, and today ovulation predictor kits) are much more recent. Thus, the first three basic elements necessary for effective solutions to this problem were not available until at best a few decades ago. What happened before then to Jewish women who had short cycles? And further, were women with short cycles the only ones at risk of reduced fertility, or did niddah laws also affect women with longer cycles? If the first three factors required for effective infertility treatment were not valid prior to the second half of the twentieth century, was the fourth factor at least valid, that the halakhically prescribed length of the niddah period for most women is twelve or eleven days? Or is this piece of the puzzle also something that we should not take for granted?

Following our discussion above, we conclude that some observant Jewish women who lived before the secrets of the menstrual cycle were discovered—and thus, needless to say, did not have the option of taking hormones to modify their cycles artificially—were denied the chance to conceive because of the niddah laws. But how many were in this situation? Are the statistics we have gathered about our own time of any value in helping us comprehend their situation? One might object to the application of modern medical data about fertility and cycles to a study of the past. Indeed, there are many issues related to fertility and women's cycles that we know were different in pre-industrialized eras. Further, there are differences even today when one compares developed and developing countries. Among the differences are the average age at which girls experience menarche (which was probably later in earlier societies)Footnote ⁶⁰ and the number of cycles a woman has in her lifetime (which was probably often much smaller).Footnote ⁶¹ Nevertheless, I am not aware of any studies claiming that the length of the cycle, and the point at which ovulation occurred, would have been significantly different. The idea that the “normal” length of the cycle is rather close to the length of a lunar month (29.5 days) is well attested since antiquity.Footnote ⁶² Today, when various populations are studied, a difference of one day in the mean length of the cycle between different communities is considered a significant find.Footnote ⁶³ Unless future studies show that women in earlier times had significantly different menstrual patterns, it seems the current medical data should not be dismissed. For a certain percentage of Jewish women, the chances of conceiving must have been positively affected by the niddah laws; but for another percentage of Jewish women, the laws had a negative effect on their fertility.

For many of those women who were negatively affected, this inability to conceive was certainly tragic. At times, they were probably offered explanations: sin, sorcery, or other metaphysical causes. Not knowing what we know today about the way the menstrual cycle works, it is unlikely that many of them suspected the niddah laws had anything to do with their misfortune. Many might have thought that the reason for their infertility was due, instead, to negligence of certain laws, and perhaps they even tried to resolve the problem by “raising the bar” of their observance. It is possible that some of them remained childless even after many years of hoping to conceive. It is likely that some of them also suffered divorce as a result of their infertility, following a rabbinic rule kept in some communities that a husband can, or even should, repudiate his wife if ten years of marriage without offspring have passed.Footnote ⁶⁴

If we adhere though to our previous estimate, based on modern medical data, that these rules would have affected only a small percentage of Jewish women, then it is unlikely that their fate would have had a palpable effect on Jewish demography. But what if—due to issues we have not yet considered—the chances of conception for a much higher percentage of Jewish women, at least in some places and times, were significantly reduced?

When Did Women Actually Bathe?

Until now, we have assumed that generally, women took their ritual baths as soon as they considered this to be halakhically permissible, whether this was on day twelve, thirteen, or fourteen of their cycles, and that they resumed sexual activity soon after. But this assumption seems to be, at least at times, problematic. Ganzel and Zimmerman report that after analyzing the medical files of 108 women who were treated for “religious infertility,” they found that only 41 percent of these women usually bathed on the twelfth or thirteenth day of their cycles. Another 24 percent usually bathed on day fourteen, and yet another 19 percent on day fifteen.Footnote ⁶⁵

Can these statistics, based as they are on a relatively small group of women, be considered representative for contemporary Orthodox women at large? I do not know. It seems many of these women went to the bath at a relatively late date because their actual period of bleeding was longer than five days. Ganzel and Zimmerman argue that, with appropriate halakhic instruction, some of these women could have still gone earlier. Can this teach us anything about Jewish women of the past? Again, I have no answer to that. But still, it might put some doubts in our perhaps too “pious” assumption that women generally went to bathe as soon as they knew they were halakhically permitted. The extremely frequent warnings, in all strata of rabbinic literature, that women should bathe immediately at the end of the “seven clean days,”Footnote ⁶⁶ very likely hints that these authors knew that many women acted otherwise.

At the very least, four issues might make us think that women in the past would have been even less likely than contemporary women to bathe promptly. The first reason as to why even very religiously meticulous women in the past may have delayed their ritual bath is a question of comfort. It is very likely that all 108 Israeli women from Ganzel and Zimmerman's study have, within walking distance or a short drive from their home, a relatively clean and heated ritual bath. This would not have been the case for many of their predecessors. Elsewhere I have argued that many medieval ritual baths were not heated.Footnote ⁶⁷ We do have significant medieval halakhic material on this issue and on disputes between women and rabbis regarding the (im)possibility of heating the water. As some of these sources hint, the refusal of women to dip into cold ritual baths in the winter was not unheard of. Simha Emanuel has also argued, and in strong terms, that

One must remember that dipping in cold water in many parts of Europe and the Middle East can be an unpleasant experience, even when winter is officially over. Perhaps in warmer seasons women did not totally avoid ritual immersion, but it is very likely that many of them did not always run to the cold bath quickly and with great excitement even when the air temperature was not too cold. It is worthwhile to remember that many studies of common birthdates and the estimated dates of conception show, not surprisingly, that couples tend to have relations in cold and temperate seasons more than in warm seasons.Footnote ⁶⁹ If meticulously observant Jewish couples avoided having relations if the wife refrained from bathing due to extreme cold, they missed a certain “intimacy peak,” followed by a birth peak nine months later, which others groups probably benefitted from.

Another possible reason why women might have delayed their bath in the past more than today is related to the scientific understanding of the menstrual cycle. One can hope that today most women have at least a basic understanding of the ovulation cycle—especially those who, as in Ganzel and Zimmerman's survey, are trying to conceive. They should know that each day, and sometimes even each hour, can make a difference between the fertilization and non-fertilization of the egg. Women of the past did not have this information. It is unlikely they would have realized that to improve their chances of conceiving, they would have had to make haste with their bath.

We can think of two other possible reasons for such delays: One is women's desire to control their fertility. Even if they did not know all the scientific facts about “how babies are made,” most women probably assumed that less sexual activity is likely to mean fewer babies. If a woman had a pious husband who would refrain from relations before his wife's immersion in the ritual bath, then delaying the bath may have served as an efficient tactic (if observed regularly and for significant periods of time) for women who did not wish to become pregnant: abstinence is obviously one of the most effective methods of contraception. The second reason is the exercise of soft power: we also know that women refrained from the bath in order to use this “embargo” on sexual relations as a way to pressure their husbands on various issues, ranging from financial considerations to requests for a divorce.Footnote ⁷⁰

It should be clear that cases like the last two—in which women delayed their bath intentionally in order to put pressure on their husbands or to prevent pregnancies—are not fully related to our scope: our interest lies only with scenarios wherein the observance of certain laws or customs affected fertility, without the couple's intention that this would be the case.Footnote ⁷¹ When the system was used intentionally by women or by couples to reduce fertility, this is certainly not something for which the laws should be blamed.

A Fourteen-Day Niddah Period

In her article mentioned above, Susan K. Gardin shows, relying on earlier studies, that if, for example, couples do not have relations until day twelve of the cycle, in 6.7 percent of cycles, ovulation might have already occurred. If they resume relations only on day thirteen, an additional 5.6 percent of the cycles will be post-ovulatory.Footnote ⁷² These are not negligible numbers, even if one might doubt the accuracy of the figures: regardless of the exact percentage, it is clear that every additional day adds an increasing percentage of “missed cycles” to the calculations. What happens if relations are delayed even more?

If women did not delay the resumption of marital relations beyond day thirteen or fourteen, the vast majority had a reasonable chance of conceiving from these relations.Footnote ⁷⁴ But maybe some did delay it, not because they did not want to engage in relations, or because they wanted to avoid conception,Footnote ⁷⁵ or because of some practical issue related to the bath, or because of lack of modern medical knowledge, but due to religious reasoning and customs?

A paragraph in the Tanhuma, a rabbinic text composed in Palestine around the middle of the first millennium c.e., hints at the existence of halakhic rules that perhaps caused a delay of relations even after day twelve or thirteen. The beginning of the text is complex and prescribes the rules that a woman who “sees blood” at various points during the “seven clean days” should follow. Then, in a finale that does not seem to be perfectly consistent with the beginning of the text, the idea of fourteen days of impurity is invoked:

A similar practice is hinted at in a paragraph in the Baraita de-Niddah, a peculiar medieval Hebrew work, which may have its origins in the Byzantine Empire during the second half of the first millennium c.e.:

Another midrashic text, which like many midrashim is hard to date but was likely composed during the second half of the first millennium c.e., incorporates the idea of fourteen days in a legendary story, imitating the plot found in the scroll of Esther. It hints at three practices: one, “biblical,” of seven days; one of fourteen days; and one of forty-eight days, a number that seems to be exaggerated for literary purposes:Footnote ⁷⁸

These three texts certainly do not provide us with proof that women actually kept a niddah period of fourteen days, which would have meant that they were not able to resume relations until the fifteenth day of their cycle. But their existence does suggest that, at the very least, such a practice was imaginable in rabbinic literature and culture, and, according to some, even desirable. Can we find proof that such an idea was ever put into practice? The answer to this question is a definitive “yes.” A number of sources from different places and times hint, and at times even say explicitly, that a practice of fourteen days of niddah was observed.

In twelfth-century France, a disciple of Salomon ben Isaac (Rashi)Footnote ⁸² recorded the existence of people who believed in the necessity of keeping fourteen days. From the disciple's perspective, his master Rashi provided winning counter-arguments to those who say “[the women] should wait seven and seven: seven days of niddah first, and then seven clean [days].”Footnote ⁸³ Yet the very existence of this debate shows that some had different opinions. The same text also mentions sources from the gaonic period (possibly two or three centuries earlier, composed in the area of current-day Iraq) that hint at similar practices.Footnote ⁸⁴

In twelfth-century Egypt, Maimonides, one of the major codifiers of law in Jewish history,Footnote ⁸⁵ explicitly attacked such a practice, although it is not clear from context whether it was known in his area or whether the “some places” to which he refers were remote ones:

References to such a practice do not disappear, although, as Eric Zimmer suggests, it is possible that observance of this custom declined during the twelfth and thirteenth centuries in the areas we now call France and Germany.Footnote ⁸⁷ In more eastern regions, references to it continue to appear in later periods. Thus, in the Archduchy of AustriaFootnote ⁸⁸ during the first half of the fifteenth century, Israel Isserlin ben PetahiahFootnote ⁸⁹ mentions the same custom in his work Terumat Hadeshen:

We have information about similar practices from a few decades later, around 1490, in the book Agur by Jacob ben Judah Landau, a German author residing in Italy. It is not easy to learn from his statement how common this practice was:

Almost a century later, around 1570, another major Ashkenazic codifier, Moses Isserles, who used Isserlin as one of his major sources, described a similar reality:

The practice of fourteen days was noted by some non-Jews. In a paragraph from a book written in the early part of the seventeenth century by Johannes Buxtorf, a German Christian observer of Jewish life, we find the following important remark: “After seven days of uncleanness, the woman counts again seven days of cleanness, and when she finds herself completely clean, she . . . has to bathe in cold water completely naked.”Footnote ⁹⁴

One should also not think that Maimonides's objection to such customs in Egypt made them disappear in non-Ashkenazic communities. Ovadya Yosef,Footnote ⁹⁵ the most important Sephardic codifier of our time, tried to fight more or less similar practices while living in Egypt in 1948. In his discussion of the matter, he also reports such practices in nineteenth-century Baghdad. He himself later encountered such a practice in Jerusalem. In that case, he commanded a woman who suffered from a violent husband not to wait seven days before counting the seven clean days but rather four, following the practices Yosef was trying to enforce:

Having seen all these texts, can we tell how common the practice of seven plus seven was, and where? Unfortunately, no. Nevertheless, it is clear not only that such a practice existed in various periods in many corners of the Jewish world but that in some circles it was actually considered the right thing to do. This should not really surprise us. From a legal, halakhic perspective, this practice makes much sense. As we have seen in Leviticus, it seems the biblical period of menstrual impurity is seven days. The talmudic rabbis also spoke of seven days, but these days were the “seven clean days,” which begin after the bleeding ends. From their perspective, the Torah's rule was just slightly extended by delaying the counting of seven days: instead of starting when the period begins, the counting begins a few days later, when the bleeding ends. Thus, they probably did not see their ruling as too radical a change from the biblical norm. The later fourteen-day practice seems to result from a similar intention. This time, the “conceptual” period of bleeding was just slightly extended beyond the length of its actual, physical occurrence. Perhaps this was influenced by a reading of the biblical rule, which also spoke of seven days (although of course not the same ones).Footnote ⁹⁷ It is not unreasonable to think that people considered a period of seven days to be a nice round number, and that two times seven cannot be a bad idea either, certainly not for those who want to show their piety.

What happened to couples who kept such a lengthy period of separation? Even if women bathed on day fifteen, their chances of conceiving were significantly reduced, as we have learned: if we use contemporary data, it is possible that 40 percent or more of their cycles were already in their post-ovulatory phase. But the reality was probably even worse. Today, as we said, when observant Jewish women (and men, one hopes) know the basics of the ovulation cycle, women who have a short cycle know how crucial it is for them to bathe and have relations as soon as they halakhically can. This was certainly not the case in the past. It is reasonable to assume that many women who kept fourteen days did not see much harm in delaying their bath another day or two. By then, and even for women who had a cycle of average length, the chances of conceiving were very low.

Thank God It's Friday!

If the scenarios described above are not bad enough from a fertility-related point of view, one can add another detail that made the situation even worse for some couples. Particularly pious couples who kept the rule of fourteen days of abstinence in each cycle (and even some observant people who did not keep this rule) were likely to observe another pietistic recommendation that appears in mainstream halakhic literature, which we briefly alluded to earlier: to have marital relations on Friday.

One might wonder why such a practice would negatively affect fertility rates. In fact, it might be argued that it would have done the exact opposite, by actually encouraging couples to have relations on a night on which they might not have been intimate otherwise. This might in fact be true for times, places, and communities in which the Friday rule did not mean relations on other nights were considered inappropriate. But what happened when this custom had the effect of channeling the entire sexual activity of observant Jewish couples to Friday night and made them generally avoid having relations on other days of the week? By exploring the development and extent of this practice, the ways it was understood, and the possibility that at some times and places religiously meticulous Jews limited their marital activity to Friday because of it, we might be able to determine whether the issue is relevant to our concerns.

The very idea that sexual relations on Sabbath Eve (and on the Sabbath Day itself) are permitted, even recommended, was not always obvious in Jewish culture, in which so many other types of human activities are forbidden on the seventh day. In fact, it is not impossible that the strong promotion of such relations is a relic from various periods in which the issue was hotly debated, a remainder from the ultimately successful campaign of the talmudic and later medieval rabbis to legitimate such relations, fighting other groups who considered them unlawful.Footnote ⁹⁸ At the same time, no matter how the issue played out during the Second Temple period, the early rabbinic period, and the medieval period, the rabbinic literature opted for a clear line, and it is this line, stipulating that sexual relations are permitted on the Sabbath, that continued to be the backbone of all subsequent discussions on the matter in the literature and culture about which we are concerned here.

In addition to the fundamental notion that sexual activity is not forbidden on the Sabbath for talmudic and post-talmudic rabbinic Judaism, the “sex on Friday” practice seems to have originated in the reconciliation of three related ideas that appear in talmudic literature. The first one is the oft-quoted talmudic-Amoraic idea that wives of rabbinic scholars are entitled to have relations with their husbands “from Sabbath Eve to Sabbath Eve.” This ruling is generally attached to a mishnaic text that discusses this issue for various professions but does not provide a rule for its most attentive readers, the scholars themselves: “The duty of marriage enjoined in the Torah is: every day for them that are unoccupied; twice a week for laborers; once a week for ass-drivers; once every thirty days for camel-drivers; and once every six months for sailors. So Rabbi Eliezer.”Footnote ⁹⁹ The talmudic editors, perhaps somewhat insulted by this disregard for their own professional guild, offer a complementary ruling:

What is the meaning of the expression “from Sabbath Eve to Sabbath Eve”? Does it require, or at least recommend, that relations be performed in the households of rabbinic scholars specifically on Sabbath Eve, or does it merely mean they should happen not less often than once a week?Footnote ¹⁰¹ As we shall see, this ambiguity gave legitimacy to both readings.

In various places in the Babylonian Talmud, one may find the notion that Sabbath Eve is indeed an apt moment for marital relations, regardless of one's profession or a man's legal obligation towards his wife. Thus, for example, a claim that the biblical Ezra commanded that garlic should be eaten on Friday—needless to say, this is a late idea and not actually mentioned in the Bible—is explained with regard to sexual relations: garlic, it is said, enhances the sperm and increases love between husband and wife.Footnote ¹⁰² Such a practice is also hinted at in a saying that, for scholars, the Sabbath's enjoyment is made by having on Sabbath's Eve “a prepared bed, and a prettified woman.”Footnote ¹⁰³ One might suspect that this textual combination of Sabbath Eve, bed, and a good-looking woman is a hint for a very specific type of activity.Footnote ¹⁰⁴ Yet another talmudic text dealing with the prescribed self-examination for women prior to and following relations to ensure they are not menstruating shows that this was a special concern on Fridays.Footnote ¹⁰⁵

A third rabbinic idea, which is somewhat related to our topic, is that marital relations performed on Saturday, Sunday, Monday, or Tuesday might increase the risk of birth on the day of the Sabbath, which would have been undesirable:

The explanation given for the practice in this paragraph, even if it is perhaps not actually the reason for the custom of those “Early Pious,”Footnote ¹⁰⁷ seems to be based on a rather simple idea: if pregnancy takes nine months, its length is 270 days (9×30).Footnote ¹⁰⁸ Adding one, or two, or three days until conception occurs following the relations would yield 271, 272, or 273 days.Footnote ¹⁰⁹ By dividing this number into weeks, one can presumably calculate the probable day of birth if the day of the week during which relations took place is known:

Even though transgressing the Sabbath to deliver a Jewish baby is allowed in Judaism as we know it (though this was not necessarily the rule in all branches of ancient Judaism), it was still considered better to prevent birth from happening on the Sabbath. As the table shows, if pregnancy is 271, 272, or 273 days in length, relations on Saturday, Sunday, and Monday carry the risk of a birth on the Sabbath. Since the sources also speak of Tuesday as inappropriate, I assume the counting of “the Early Pious” included also the possibility of a birth on the day we would count as the 270th. Although the avoidance of Sabbath births is not specifically mentioned by talmudic editors as a reason for prescribing relations on Friday, it would make Friday one of most appropriate three days for intercourse, together with Wednesday and Thursday.Footnote ¹¹⁰

How were all these sporadic and at times ambiguous talmudic statements connecting the Sabbath Eve with marital relations understood in later generations, those generations on which our study actually focuses? Many texts seem to hint that two interpretations often existed side by side: on the one hand, that Sabbath Eve is an apt moment for relations but that does not exclude other nights; on the other hand, that Sabbath Eve is the right timeFootnote ¹¹¹ and other moments during the week, although not forbidden, are significantly less appropriate for this type of activity. In fact, many of the statements on the matter remain ambiguous and can be interpreted either way. Because the more interesting ones for our purposes are those that clearly support, or hint at, a “Friday only” attitude, or at least a “best on Friday” one, we will mention here only a few examples of this kind from the post-talmudic period.Footnote ¹¹²

In medieval Europe, Salomon ben Isaac (Rashi), one of the most important Jewish authors of all time, who was already mentioned above, was quick to explain that a reference to “Sabbaths Eves” in a certain talmudic text is there because this is the appropriate moment for “pious and scholars” to have marital relations.Footnote ¹¹³

In kabbalistic literature, the idea that marital relations should be specifically performed on Friday is commonly found. It appears in one of its most fundamental books, the Zohar, the core of which was composed in Castile in the thirteenth century. There, we learn in several places that relations on Friday are particularly appropriate because they coincide with the union that happens at the same time in the divine realms. Thus, for example, a biblical text from the book of Isaiah is given an entirely new meaning:

The notion that scholars should only have intercourse on Friday is also found in many works by authors for whom the Zohar was a major source of inspiration. Menahem Recanati, an Italian kabbalist from the same generation, mentions it several times in his biblical commentary.Footnote ¹¹⁵ It is also discussed extensively in the third chapter of the rather famous “Holy Letter” produced around the same time,Footnote ¹¹⁶ as well as in an earlier text of a somewhat similar genre, the Ba'ale Hanefesh of the twelfth-century author Abraham ben David of Posquières.Footnote ¹¹⁷ “Mystics were exhorted to have relations on Friday night alone,” summarizes Sharon Koren.Footnote ¹¹⁸ This idea appears also in a later mystical wave among the kabbalists who were active in the Galilee in the sixteenth century. Thus, for example, Moses ben Makhir, the head of a school in Ein Zeiton, near Safed, in the second half of that century, mentions a local custom in which men would go to bathe on Friday afternoon with their wives; the suspicion that this practice was related not only to a general preparation for the Sabbath but also to marital relations that evening seems very likely.Footnote ¹¹⁹ Another major kabbalist from the same time and place, Moses ben Jacob Kordovero, reminds his readers of an earlier idea that Adam and Eve, having been created on Friday, were supposed to have marital relations on Sabbath Eve in the Garden of Eden. Unfortunately, they sinned before that time and were expelled: the most opportune time for relations was missed. Readers of his work should try harder.Footnote ¹²⁰

The “Friday sex” idea appears also in the three most important Jewish legal codes: Maimonides's Mishneh Torah of the twelfth century, the fourteenth-century Arba'ah Turim of Jacob ben Asher, and Joseph Karo's Shulhan Arukh, composed in the sixteenth century. Maimonides mentions it in a list of professions and their required sexual activity. His list is more or less similar to the one given in the Mishnah, but it ends with his addition: “Torah scholars should fulfill their conjugal duties once a week, because the Torah weakens their strength. It is the practice of Torah scholars to engage in marital relations from Sabbath Eve to Sabbath Eve.”Footnote ¹²¹

By seamlessly combining in his statement both the Mishnah, which does not speak about scholars, and the later talmudic statement that says their required frequency is once a week, and by talking about scholars again in the last sentence, Maimonides conveys two points: that scholars’ special day for marital relations is Sabbath Eve; and that, although this is ideally their common practice, it is still only a custom, not a binding law. When Maimonides repeats this law in other places, it is obvious that sometimes he means not only once a week but Sabbath Eve itself, while at other times he means a weekly practice. This seems again to suggest that he wants to make a clear distinction between the law (once a week) and the custom (on Sabbath Eve):

Shlomo Goitein, in one of his articles regarding what he calls “the genizah society”—that is, the society attested in the Cairo Genizah, the collection of dis-carded old books and documents found in an ancient synagogue in Cairo, the society of which Maimonides himself was a part—remarks that the practice of sexual relations on Friday nights and holidays seemed to be common: “Since every Jew liked to look upon himself as a scholar, it became the rule, and failure to observe it entailed legal consequences.”Footnote ¹²⁵ Goitein seems to stress particularly the fact that Friday preceded the day of rest for Jews. After noting several mentions of such a practice from the genizah, Goitein remarks that this custom was not dissimilar to a Muslim practice, and he makes an interesting suggestion: “For Muslims, the night preceding Friday, their holy day, played a similar role, and I suspect that the entire matter had its origin in ancient Greek medical advice on sound hygiene.”Footnote ¹²⁶

Maimonides's discussion of the issue in his central halakhic work was certainly not unique. In the next major successful attempt to codify Jewish law, the Arba'ah Turim of Jacob ben Asher in the fourteenth century, the topic appears in two places. Jacob ben Asher does not make an effort to be more specific than the Talmud itself, as he simply uses the same expression: “The marital obligation of Torah scholars is from Sabbath Eve to Sabbath Eve.”Footnote ¹²⁷ The following major code of Jewish law, the sixteenth-century Shulhan Arukh of Joseph Karo, uses the same expression, although in one place it emphasizes—by repeating almost verbatim Maimonides's words on the subject (quoted above)—that the appropriate moment for marital relations for scholars is on Sabbath Eve.Footnote ¹²⁸

With all these major sources mentioning the practice of scholarly sex on Friday, it is not surprising that it continues to be referred to in many later works, and it seems very reasonable to assume it was well known at least among learned Jews, if not in larger circles. Calls such as the one found in the fourteenth-century book Orhot Hayyim—which states in regard to the practice: “And every man should behave like a scholar,”Footnote ¹²⁹—might have made the practice a goal for many. Even today, in some Orthodox circles, Friday night is called at times “mitzvah (commandment) night,” with the understanding that the mitzvah in question is of a very distinct nature.Footnote ¹³⁰

What happened when people acted on this recommendation? When pious couples had sexual activity almost exclusively on Friday, what was the impact of this practice on their fertility? As so many factors are again involved, it is unlikely that we can ever provide a clear answer to such a question. To add to the ambiguity, in quite a number of sources the prescription of this practice is accompanied by a statement that a man should also have relations with his wife on the night following her ritual bath.Footnote ¹³¹ If the bath was taken early enough in the cycle, and if the woman did not have a particularly short cycle, such relations obviously could have led to conception. It is also possible that this “Friday rule” actually pushed couples who would otherwise not have frequently engaged in marital relations to have them out of piety at least once a week when the woman was pure. In that case, the rule would have actually increased, and not decreased, their sexual activity. Other authorities even add additional days on which relations are commendable, days that become in a way “pseudo-Fridays”: certain holidays and the day (or days) marking the new month. How can we take these practices into account?

The issue is certainly complex. I tend to suspect that generally, if the practice of limiting relations (almost) exclusively to Fridays had any impact on pious couples’ chances of conceiving, it was not a positive one, but I doubt we can ever come to a definitive answer about this question.

Proofs from Reality?

Let us again put aside the possibility that some couples limited their sexual activity to only Friday and return to discussing those couples who followed the fourteen-day rule we explored above, without further limiting their sexual activity by the “Friday only” custom.

In fact, the analysis of both medical data and halakhic material done thus far leaves us with what seems to be a clear-cut understanding: most women, if they have relations only after day fourteen or fifteen of their cycle, dramatically reduce their chances of conceiving. If for whatever reason these women delay relations even more, they are unlikely to conceive at all. Women who meticulously followed halakhic recommendations or communal customs that encouraged or legitimized such delays—miracles aside—inevitably would have had lower rates of fertility than women who did not follow these customs. Several halakhic texts confirm that such practices existed at different times and places, but none of the sources we have seen so far has hinted that this created a reduction in fertility. Theory aside, can we prove that this indeed happened to some women?

If one awaits absolute, irrefutable proof, the answer is probably no. Anyone who has ever dealt with social history of medieval or ancient communities knows how hard it is to gather information on a significant portion of the population. We often have some solid information on the lives of kings and rulers. We know very little about their subjects. Often, all we have are hints. I hope that the way I interpret some of these hints will be considered by the readers of this article to be at the very least plausible.

An important codifier who lived in Provence in the thirteenth and early fourteenth century had, I believe, suspicions similar to mine. If this is true, it is particularly remarkable, as he certainly did not have the scientific understanding we have today. I am referring to a peculiar statement made by Menahem ben Salomon Hame'iri:Footnote ¹³²

What could Menahem ben Shlomo have meant in his statement that the harm of such a practice “is obvious to whoever is knowledgeable regarding the places from which these instructions come”? What could have been so bad in those places? How can an additional day, or even two, of abstinence create a noticeable “harm”? Although this is impossible to prove, I suspect that the issue at hand was in fact serious. The low fertility rate in such communities must have been apparent to attentive people. Menahem ben Salomon Hame'iri did not know about ovulation, religious sterility, or hormones. But it is possible he had a keen eye to realize that something was amiss in places where such a practice was common. As we saw earlier, other authors such as Maimonides attacked similar customs for halakhic reasons, insisting that these practices had no valid basis. Menahem ben Salomon does not base his attack solely on halakhic sources. He also speaks using his own observations of reality. From this perspective, his testimony is precious and, as far as I know, unique.

Sefer Hasidim, one of the most fascinating Jewish documents of the Middle Ages, of which at least significant parts were composed in thirteenth-century Germany, contains the following story: “It was said that in one place there were many women, but only a few were pregnant, while in another place almost all women were pregnant. A sage was asked about it. He said: ‘You should know that I investigated the issue.’ ”Footnote ¹³⁴ This sage's findings are not relevant to our issue. According to him, the reason was some mélange of witchcraft and monetary interests, not ovulation and hormones. Obviously, the literary genre of this particular text hinders the possibility of gleaning from it any historical data of value. Nevertheless, would it be totally impossible to suggest that the story might stem from some observation of the author? Can it not be used as proof that there was at least some awareness among medieval Jews that significant differences existed between the fertility rates of women in different communities?

In an article in 1987, Kenneth Stow showed that Jewish families in the twelfth-century Rhine area were very small.Footnote ¹³⁵ He based his conclusions on a study of Jewish memorial books, in which, often after deadly persecutions, the names of the victims and their family ties were recorded. Unlike accounts saying things such as “hundreds died,” which are needless to say very problematic, these memorial books seem to be a relatively reliable source: due to the authors’ respect for the dead and the use of these books in ad memoriam liturgy, they tried to be accurate and precise.

According to Stow's findings, in about 18 percent of these Rhine area families there were no children, and in another 67 percent there were only one or two. The average number of children in that society was 1.77 per family.Footnote ¹³⁶ In another sample of Jews in the same area but in the late thirteenth century, Stow's findings were practically the same. Although this low number of children is surely related more to high childhood mortality than to extremely low fertility, and although it seems Christian families were also not as large as some might imagine,Footnote ¹³⁷ one is tempted to suggest that in addition to voluntary contraceptive methods, some Jewish religious practices contributed—possibly unintentionally—to a low rate of fertility.Footnote ¹³⁸ Pietistic practices of many kinds were developed in precisely these communities.Footnote ¹³⁹ The argument can also go in another direction: even if one might argue that this low number of children was not related to niddah practices, in communities with such a low number of living children to begin with, every small factor that influences fertility can have a tremendous impact on the continuation of families.Footnote ¹⁴⁰ Even if one might argue that Jewish religious practices reduced the fertility of only a small number of women, it is very possible that for many of them such a reduction meant the difference between having one child and having none at all.