Data

Data for this study were obtained as part of ALSPAC, an ongoing population-based study designed to investigate the effects of a wide range of influences on the health and development of children.

Study population

Pregnant women residing in the Avon area of south-west England who had an estimated date of delivery between 1 April 1991 and 31 December 1992, were invited to participate in the study. It was estimated that 85–90% of the eligible population participated. ^{Reference Golding, Pembrey and Jones20} All data used for this study were collected via postal questionnaires. The study cohort consisted of 14 541 pregnancies and 13 998 children who were still alive at 12 months of age. The study protocol has been published previously, ^{Reference Golding, Pembrey and Jones20} and further details can be found at: www.bris.ac.uk/alspac. Ethical approval for all measures was obtained from the ALSPAC Ethics and Law Committee and from local research ethics committees. The current study focuses on the 13 133 women for whom we had data on previous prenatal loss. The data for the current study are based on six assessments, two during pregnancy at 18 and 32 weeks’ gestation, and four in the postpartum period, at 8 weeks and 8, 21 and 33 months.

Measures

Statistical analysis

Generalised estimating equations (or GEE) is a method used for longitudinal data modelling. This method is semi-parametric and therefore does not require normal distribution assumptions to be met. Given that depression and anxiety can be treated as discrete or continuous data they do not meet normality assumptions for parametric data analysis. The GEE was performed to model the change of depression and anxiety over time. A backward elimination procedure was applied to control covariates and interactions. It should be noted that there were a significant number of missing values for depression and anxiety, especially for the last two visits. Specifically, sample sizes at the six visits were 12 121, 12 096, 11 710, 11 195, 10 259 and 9683. The impact of missing data was characterised by model estimates through two well-established missing data mechanisms: the missing completely at random assumption and the missing at random assumption. ^{Reference Robins, Rotnitzky and Zhao26} The missing completely at random assumption was tested by modelling the missingness as a function of observed responses and baseline covariates using logistic regression. It was found that depression at previous visit was a strong predictor, thus the missing completely at random assumption is inappropriate and weighted generalised estimating equations (WGEE) were used with weights estimated from the logistic model for missing data. ^{Reference Robins, Rotnitzky and Zhao26}

Supplementary analyses

Analyses were re-run using categorical cut-off scores for depression and anxiety rather than a continuous scale. We found substantively comparable results using this alternate scaling. Given the overlap between depressive and anxious symptoms across the reproductive period, a final set of regression analyses (not reported; details available from the author) was carried out to investigate whether the effect of prenatal loss on anxious symptoms was distinguishable from that for depressive symptoms and vice versa. It was not. The association between prenatal loss and anxious symptoms was confounded by the association between prenatal loss and depressive symptoms and the high degree of covariation between anxious and depressive symptoms (>r = 0.70 at each assessment).

Fig. 1

Mean (95% CI) of (a) depression and (b) anxiety symptom scores throughout the perinatal period according to number of previous prenatal losses (miscarriages + stillbirths).

Numbers of participants are as follows: zero losses, n = 10 250; one, n = 2158; two, n = 515; three, n = 131; and four or more, n = 79.

Main findings

We found no evidence that affective symptoms associated with previous prenatal loss resolve with the birth of a healthy child. Rather, previous prenatal loss showed a persisting prediction of depressive and anxiety symptoms well after what would conventionally be defined as the postnatal period. There were changes over time in the perinatal period in depression and anxiety, but these did not vary significantly for women with different histories of prenatal loss. The predictions of anxious and depressive symptoms were similar and inseparable, the result of comparable effect sizes and the high degree of overlap between the two dimensions. Previous studies had documented that women who had experienced miscarriage or stillbirth had significantly higher levels of anxiety and depression in a subsequent pregnancy. ^{Reference Janssen, Cuisinier, Hoogduin and de Graauw5,Reference Thapar and Thapar9,Reference Beutel, Deckardt, Von and Weiner6,Reference Armstrong and Hutti27} The current study extends this work by showing that the impact persists well past the subsequent pregnancy and despite the birth of a healthy child (indexed here by birth weight and gestational age of the subsequent child).

Findings from other studies

Our findings of prolonged and elevated depressive and anxious symptoms in women with a prior prenatal loss nearly 3 years after the birth of a subsequent child contrast with some previous studies. Hughes et al ^{Reference Hughes, Turton and Evans14} found that, compared with controls, women who were pregnant subsequent to a stillbirth had significantly higher levels of depression and state anxiety during pregnancy, but did not differ from controls at 6 and 26 weeks postpartum. Interestingly, the subset of women who conceived less than a year following the stillbirth had significantly higher depression and anxiety scores across all time points than women who conceived after a year. The possibility that time since previous prenatal loss moderates the persisting impact of distress could not be examined in this study because we did not have reliable information on the timing of the previous loss. It may be that a more recent loss is associated with higher levels of affective symptoms that continue in the postpartum period, perhaps as a function of bereavement. ^{Reference Beutel, Deckardt, Von and Weiner6,Reference Hughes, Turton and Evans14}

Although Armstrong et al ^{Reference Armstrong, Hutti and Myers18} also reported that depressive and anxious symptoms during pregnancy decreased following the birth of a healthy child, they noted that mothers with higher levels of depression and anxiety in the postpartum period reported increased concerns about their investment in and health concerns about their infant. This raises the important issue of how and whether previous perinatal loss and associated mood symptoms may alter child outcomes. Limited available data suggest that mothers may have more concerns about and greater difficulty managing the needs of a child born after a prenatal loss; ^{Reference Hunfeld, Taselaar-Kloos, Agterberg, Wladimiroff and Passchier19,Reference Theut, Moss, Zaslow, Rabinovich, Levin and Bartko28} also, 12-month-old infants born following prenatal loss were reported to show higher rates of disorganised attachment patterns to their mothers than children born into families without a loss history. Thus, even if there is no persistence of mood disturbance into the postnatal period, there may still be adverse effects of a previous prenatal loss on the parent–child relationship and child outcomes. This possibility requires further attention.

Brockington ^{Reference Brockington31} has argued that pregnancy and childbirth should be seen as a general stressor, like any other life event that can potentially trigger an affective illness episode. ^{Reference Brown, Harris and Hepworth32} The current findings underscore the view that pregnancy and childbirth are major life events, a careful assessment of which may reveal information of value in understanding psychiatric morbidity.

Clinical implications

There are important clinical implications of this work. Currently, prenatal loss is not routinely considered a risk factor for antenatal or postpartum depression in the same way as, for instance, personal or family history of depression, exposure to stressful life events or lack of social support. Our findings suggest that routinely assessing loss history, which could be accomplished briefly and without some of the report bias that accompanies other assessments, would be valuable as a predictor of current and postpartum risk and as a possible marker for intervention. Approximately 15% of women experience clinically significant antenatal depression and anxiety ^{Reference Heron, O'Connor, Evans, Golding and Glover33} and so recognition of and effective treatment for perinatal mood disturbance are of the utmost importance. Both prenatal depression and anxiety are among the biggest predictors of postpartum depression, ^{Reference Robertson, Grace, Wallington and Stewart34,Reference O'Hara and Swain35} which in turn has deleterious effects on maternal–child attachment, child behaviour, and cognitive and neuroendocrine outcomes that persist into adolescence. ^{Reference Halligan, Herbert, Goodyer and Murray36–Reference O'Connor, Heron, Golding, Beveridge and Glover40} Given the adverse outcomes of persistent maternal depression on both child and family outcomes, early recognition of symptoms can lead to preventive interventions to reduce the burden of illness, provide coping strategies to reduce anxiety and depression and promote healthy adjustment of the mother, family and child.

Strengths and limitations

Strengths of the study include the large community sample and detailed and repeated assessments of depressive and anxiety symptoms in the prenatal and postnatal period; the follow-up well past the postnatal period is a particular novelty in this area of study. There are, however, limitations. Participants were asked about the number of miscarriages and stillbirths experienced retrospectively, which could be subject to recall bias. However, the objective nature of the event provides some protection against this possibility, and the persistence of effect years after the enquiry about perinatal loss makes a simple recall bias account unlikely. Self-reports of prenatal loss may be underestimated insofar as mothers are often unaware of spontaneous early miscarriages. ^{Reference Martin, Kochanek, Strobino, Guyer and MacDorman4} Accordingly, the current study is able to assess the psychological impact of prenatal loss, but is not positioned to examine biological hypotheses that there may be risk underlying both prenatal loss and the experience of depressive and anxiety symptoms. Finally, as noted, we were unable to assess the impact of time since loss as a potential predictor of postpartum mood.