Introduction
According to the World Health Organization, a consanguineous marriage is defined as a marriage of a couple who are related as second cousins or closer. It is estimated that globally about 20% of the human population live in communities with a preference for consanguineous marriage, and that at least 8.5% of children have consanguineous parents (Alwan & Modell, Reference Alwan and Modell1997). The prevalence of consanguinity and rate of first cousin marriage can vary widely within and between populations and communities, depending on ethnicity, religion, culture, economy and geography. Populations in the Middle East, North Africa, South-West Asia and South India favour consanguineous marriages, where total consanguinity rates reach 20–50+% of all marriages. Consanguineous marriages are also practised among communities who have emigrated from highly consanguineous countries such as Pakistan, Turkey, North Africa and Lebanon to reside in Europe, North America and Australia (Hamamy & Alwan, Reference Hamamy and Alwan1994; Modell & Darr, Reference Modell and Darr2002; Bittles, Reference Bittles2008; Hamamy et al., 2011).
Arab communities favour cousin marriage for many reasons including the idea that consanguinity strengthens family ties, that it is more favourable for the women's status, that the husband and wife share the same social standards, and that it keeps the owned property within the family (Bittles, Reference Bittles2001). Factors that may have an influence on the consanguinity rates in Arab countries include, among others, the area of residence of families within the country (urban/rural), the education levels of parents and their religion (Hafez et al., Reference Hafez, El-Tahan, Awadalla, El-Khayat, Abdel-Gafar and Ghoneim1983; Al-Awadi et al., Reference Al-Awadi, Moussa, Naguib, Farag, Teebi, el-Khalifa and el-Dossary1985; Khoury & Massad, Reference Khoury and Massad1992; Al-Arrayed, Reference Al-Arrayed1995; al-Gazali et al., Reference Al-Gazali, Bener, Abdulrazzaq, Micallef, Al-Khayat and Gaber1997; Jaber et al., Reference Jaber, Halpern and Shohat2000; Rajab & Patton, Reference Rajab and Patton2000; Al-Arrayed, Reference Al-Arrayed2005b; El-Mouzan et al., Reference El-Mouzan, Al-Salloum, Al-Herbish, Qurachi and Al-Omar2007; Barbour & Salameh, Reference Barbour and Salameh2009).
This study reports the consanguinity rates between parents of Bahraini newborns during 2008–2009 in comparison with the rates reported in previous studies in the same population from the years 1990 to 2006.
Methods
A newborn screening programme in Bahrain was started in May 2007. The nurses in the maternity units in Ministry of Health (MOH) hospitals have to fill in a form focusing on certain demographic data of the newborn, the mother and the father. The form includes a question about possible consanguinity among the parents of the newborn. Categories of consanguinity were divided into first cousin marriages, far relation and non-consanguineous. The category of far relation defined all marriages beyond first cousins including those beyond second cousins.
From 1st September 2008 to the end of December 2009, a total of 3989 newborns in 2008, and a total of 10,248 newborns in 2009 were included in this study. The consanguinity status among the parents of all newborns in the study was recorded and analysed. These numbers cover all the newborns delivered in the MOH maternity hospitals during that period, which amount to 75% of all Bahraini deliveries. It is noted that the number of all deliveries in Bahrain during the year 2009 was 17,841, including 13,487 Bahraini newborns and 4354 non-Bahraini newborns. Amongst the total deliveries, 11,561 newborns were born in MOH hospitals (65%), 29.5% were born in private hospitals and 5.5% were home deliveries. Private hospitals are a new addition to Bahrain's health care facilities, which started their services during the past 5–8 years. Newborns delivered in private hospitals were not included in this study.
Comparison between the consanguinity rates among Shia' and Sunni in Bahrain cannot be elicited in this study as the demographic data collected by the MOH and in the questionnaire sheets did not include questions on whether the parents were Shia' or Sunni. However, it is generally thought that in Bahrain consanguineous marriages are common in the tribal population as well as among both Shia' and Sunni affluent families. The data were computerized and the SPSS program was used for analysis. The results were compared with those of previous consanguinity studies done in Bahrain.
Results
A total of 3989 newborns were included in the period September to December 2008. In 3554 (89.1%) of the cases there was no consanguinity among the parents. First cousin marriages were reported in 275 couples (6.9%) and far relation marriages were reported in 160 couples (4%). The total consanguinity rate was 10.9% (Table 1).
Consanguineous marriages among 3989 couples assessed during newborn screening in Bahrain from 1st September 2008 to 31st December 2008
Throughout the year 2009, the total number of newborns was 10,248. In 9081 newborns (88.6%), there was no consanguinity among parents. First cousin marriages were reported in 695 couples (6.8%), and far relation marriages were reported in 472 couples (4.6%). The total consanguinity rate was 11.4% (Table 2).
Consanguineous marriages among 10,248 couples assessed during newborn screening in Bahrain from 1st January 2009 to 31st December 2009
The results of four previous studies on consanguinity rates in Bahrain from 1990 to 2006 (Al-Arrayed, 1995, 2005b, 2006; Tawfeeq et al., 2000), as well as the results of this study, are presented in Table 3 and Fig. 1. A decline in both first cousin and total consanguinity rates was evident from 1990 to 2008–09. The only previous study involving more than 5000 families was the study done in 1995 (Tawfeeq et al., Reference Tawfeeq2000; Al-Arrayed, Reference Al-Arrayed, Tadmouri, Taleb and Al Khaja2006). Although the working definition for consanguineous marriages includes only second cousins and closer, reports on consanguinity rates may include marriages between third cousins or far relatives within the consanguineous category. This would affect the total consanguinity rate but does not markedly alter the average inbreeding coefficient. Therefore, for comparison of consanguinity rates among populations, two parameters are best used: the mean inbreeding coefficient (α) and marriages between first cousins. Due to variable definitions for far relatives in different studies done in Bahrain, we opted to use statistical analysis to compare only the first cousin marriage rates because this category was very well defined and reported in all studies.
Secular changes in consanguineous marriages in Bahrain, 1990–2009
Decline in consanguineous marriage rates in Bahrain 1990–2009.
First cousin marriage rates showed a statistically significant decline (p<0.001) over a period of 10 years, as evident from the comparison of the results of this study on 10,248 families with the results of 1995 study on 26,724 families (Tawfeeq et al., Reference Tawfeeq2000).
Discussion
The genetic unit at the Salmaniya Medical Centre was established in 1984, with the aim of studying genetic diseases and implementing a plan to reduce the prevalence of these diseases, especially genetic blood diseases, in Bahrain. A comprehensive community genetic programme was implemented that included intensive education and awareness campaigns and population screening programmes with subsequent genetic counselling (Al-Arrayed, Reference Al-Arrayed2005b). During this campaign, advice against cousin marriages was avoided, as recommended by the World Health Organization (WHO). The campaign included premarital counselling (PMC) with information on the risks of consanguineous marriages if both partners are carriers of the same autosomal recessive gene and discussion of the option of prenatal diagnosis whenever feasible. The campaign continued for more than 20 years, and was successful in reducing the prevalence of genetic blood disease, specifically that of sickle cell anaemia, in the country by 70% over a period of 20 years (Al-Arrayed, Reference Al-Arrayed, Hafadh and Al-Serasi1997, Reference Al-Arrayed2005a, Reference Al-Arrayed, Tadmouri, Taleb and Al Khaja2006; Al-Gazali et al., Reference Al-Gazali, Hamamy and Al-Arrayad2006).
Comparison of the results of this study with previous studies from 1990 to 2006 indicated that the consanguinity rates in Bahrain have declined over a period of 20 years, with first cousin marriage rates declining from 24% in 1998 to 6.8% in 2009. The first study on consanguineous marriages in Bahrain was conducted in 1990 on a group of 500 young married Bahraini women. The consanguinity rate was 39.4% in the studied generation (fathers and mothers) and 45.5% in the previous generation (grandfathers and grandmothers), indicating a high rate of consanguinity that showed a secular decline. The rate of first cousin marriage in the studied generation was 21% (Al-Arrayed, Reference Al-Arrayed1995). In 1995, and through a National Family Health Survey, a total of 4166 households were interviewed. This included 26,724 persons. Consanguinity and first cousin marriages rates were 32% and 24% respectively (Tawfeeq et al., Reference Tawfeeq2000). The third study was the neonatal screening for haemoglobinopathies performed in 2002, where consanguinity rates and first cousin marriages among 2000 families were 20% and 12.5% respectively, indicating a substantial decline when compared with the rates reported in 1995 (Al-Arrayed, Reference Al-Arrayed2005b). The fourth figure came from the premarital counselling study in 2006. Consanguinity rates and first cousin marriages among 500 couples were 20% and 11.4% respectively, figures that are very similar to those reported in 2002 (Al-Arrayed, Reference Al-Arrayed, Tadmouri, Taleb and Al Khaja2006).
The high level of literacy and education among the people in Bahrain in general, and the campaign to prevent genetic disease in particular, may have helped to achieve the observed decline in the rate of genetic blood diseases, and the rate of cousin marriages in the country. Apart from Bahrain, secular decline in the consanguinity rates has been noticed in other Arab populations such as among Jordanians (Hamamy et al., Reference Hamamy, Jamhawi, Al-Darawsheh and Ajlouni2005) and Palestinians (Assaf & Khawaja, Reference Assaf and Khawaja2009; Sharkia et al., Reference Sharkia, Zaid, Athamna, Cohen, Azem and Zalan2008). Several factors may contribute to this decline in the consanguinity rates, including the increasing higher female education levels, the declining fertility resulting in lower numbers of suitable relatives to marry, more mobility from rural to urban settings, and the improving economic status of families. On the other hand, social, religious, cultural, political and economic factors still play their roles in favouring consanguineous marriages among the new generations just as strongly as they did among the older generations in the Middle East and North Africa. In fact, consanguinity seems to be increasing in some Arab countries including Qatar (Bener & Alali, Reference Bener and Alali2006) and Yemen (Jurdi & Saxena, Reference Jurdi and Saxena2003), possibly because of a belief that the social benefits of consanguineous marriages can outweigh the genetic risks. It is believed that the practice of consanguinity promotes family stability and has some social and economic advantages. The ongoing strong preferential culture of close kin marriages in many societies, and among migrant communities in Western countries, merits an equivalently detailed assessment of the social and genetic benefits of consanguinity in future studies (Hamamy et al., Reference Hamamy, Antonarakis, Cavalli-Sforza, Temtamy, Romeo and Ten Kate2011).
In all cases, reports on secular trends in consanguinity need to be treated with some caution because in countries where consanguinity is favoured, major regional and ethnic differences in prevalence are commonly observed (Bittles, Reference Bittles2008).
Conclusion
Consanguinity rates continue to decline in Bahrain as genetic education and awareness campaigns expand. It is expected that this decline in consanguinity rate could have a role in decreasing the rate of rare autosomal recessive disorders among future generations in Bahrain.
