In summary, our results highlight several important correlates of depressive symptoms during pregnancy, including maternal anxiety, life stress, prior depression, lack of social support, domestic violence, unintended pregnancy, relationship factors, and public insurance. Life stress, lack of social support, and domestic violence continued to be associated with antepartum depressive symptoms in multivariate analyses.
In general, our findings regarding antepartum depression are consistent with those of previous metaanalyses that evaluated postpartum depression.5-8
However, while 2 of the postpartum metaanalyses6,8
found an association between SES and postpartum depression, our review showed no association between composite SES measures and antepartum depression. This disparity could be due to the fact that their metaanalyses evaluated risk factors for postpartum depression, while our review focused on risk factors for depression during pregnancy. Also, the studies in our sample tended to compare SES within homogeneous patient populations. The lack of variability within each study sample could have decreased the power to detect an association. In addition, the power of our review to detect an association was limited by the fact that we did not use metaanalytic techniques. Third, the lack of an association between SES and antepartum depression may be due to true mediators that explain this phenomenon, such as chronic stress.69
Finally, SES may not be directly associated with antepartum depressive symptoms, but it may moderate the relationship between other risk factors and depression during pregnancy.
We were also surprised to find few multivariate studies assessing a history of depression. In postpartum reviews,7,8
lifetime depression history has proven to be a potent risk factor for postpartum depression; and indeed, in bivariate analysis, our results demonstrated a significant relationship between a history of depression and depressive symptoms during pregnancy. Our multivariate analysis of depression history was limited by sample size, as we found only 3 high-quality studies that addressed this risk factor in multivariate models. Each of these 3 studies used a different method to assess for a history of depression, and none of the 3 used Diagnostic and Statistical Manual of Mental Disorders criteria. In addition, this body of evidence generally referred to a history of depression as occurring at any point in a woman’s life. There were insufficient data to examine whether there is specific risk associated with a history of perinatal depression, such as a history of postpartum depression.
We should highlight several general limitations to the current body of evidence. First of all, there is significant heterogeneity among studies, including differences in the screeners that are used, the populations that are studied, the risk factors that are addressed, and the confounders that are controlled for in statistical analyses. In addition, only a third of the studies controlled for any confounders in a multivariate model. This heterogeneity limited our ability to summarize the evidence for any given risk factor and precluded the use of metaanalytic techniques.
In addition, most studies used depression screening tools but did not perform diagnostic assessments for depression. Studies also used different cutoff points on screening tools to determine clinically significant symptomatology. These limitations constrain our ability to determine the predictive validity of the risk factors studied.
Similarly, most studies in our sample were cross-sectional in design, limiting the ability to draw conclusions about the direction of causality. For example, a woman who is depressed during pregnancy may be more likely to recall the conception as unintended or may be more likely to view her social network as lacking.
In response to these limitations, we make several suggestions for future research. First of all, authors should attempt to use consistent screening tools so that cross-study comparisons evaluate similar outcomes. In addition, more studies should include diagnostic assessments for depression when examining risk factors. Such data would allow us to determine the predictive validity of using such risk factors in clinical practice. Finally, we need more longitudinal study designs to examine causality between potential correlates and depressive symptoms.
We should also point out several limitations to our analysis of these data. While we attempted to minimize publication bias by searching multiple databases and the grey literature (the body of materials that cannot easily be found through conventional channels; eg, dissertations, conference abstracts, and medical guidelines), it is possible that such a bias still existed. In addition, we limited our analysis to studies in English and in developed, mostly westernized countries. Therefore, our results are only generalizable to such populations. However, there is still cultural heterogeneity within these regions and this may have affected our results. Also, while we attempted to develop a valid quality assessment tool for the articles in our sample, the assessment of quality is inherently a subjective process. Finally, this is a systematic review of mostly observational studies. Due to the inherent nature of observational study design, we cannot ensure that all potential confounders were controlled for in studies with multivariate models.
Despite these limitations, our results demonstrate several correlates that are consistently related to increased risk of depressive symptoms during pregnancy. As major depression affects up to 12.7% of our prenatal population1
and ACOG recommends routine depression screening for all pregnant patients,2
it is imperative that obstetric providers are educated about identifying antepartum depression. Our results are important for practicing clinicians because they identify risk factors that can be assessed during routine obstetric care. For current practice, providers should especially consider the likelihood of depressive symptoms in women with these risk factors, such as report of domestic violence or a lack of social support during pregnancy. Reminder boxes for history of depression and domestic violence are included in the ACOG Antepartum Record.13
Future work should address how well our current obstetric screening forms capture these constructs and how we can use risk factor identification to improve screening efficiency and accuracy and to enhance our clinical assessments during pregnancy. For example, future research studies could evaluate the likelihood of major depressive disorder in women with positive depression screens that do or do not have these additional risk factors.