About 10% to 15% of women experience depression during the first year of childbirth. Some of the earliest studies identified depression during pregnancy as a strong predictor of postpartum depression. Other studies have shown that for many women with postpartum depression, depressive symptoms begin during pregnancy and worsen after delivery.
A more nuanced understanding of the continuum of depressive symptoms during pregnancy and the postpartum period has important clinical implications and could inform the timing of screening for perinatal mood and anxiety disorders.
A recent study conducted a systematic review and meta-analysis estimating the prevalence of postpartum depression (PPD) at different time points in women who experienced antenatal depression at different times during pregnancy.
The researchers identified cohort studies that looked at the prevalence of PPD in women who were depressed during pregnancy (prenatal depression or AD) and studies that looked at the relationship between AD and PPD. The analysis included 88 cohort studies with a total of 1,042,448 perinatal women.
- About 37% of pregnant women who had AD later developed PPD. Women with antenatal depression had a 4.58 times greater risk of developing PPD (OR: 4.58; 95% CI = 3.52-5.96).
- The likelihood of PPD was higher when antenatal depression was experienced in the first or third trimester compared to the second trimester. About 12.8% of PPD cases were attributable to AD.
- Among women with PPD, 16.3% also had depression during pregnancy.
In this meta-analysis of more than one million perinatal women, women who experienced depression during pregnancy were approximately four times more likely to develop PPD compared with women without depression during pregnancy, a finding similar to previous studies. Furthermore, depressive symptoms experienced during the first trimester were as strongly associated with PPD as depressive symptoms during the third trimester.
What are the clinical implications?
This study shows that women who experienced depression during pregnancy had more than four times the risk of developing PPD than women without prenatal depression. The odds of PPD were higher when antenatal depression was experienced in the first or third trimester compared to the second trimester. The findings of the current study are consistent with previous studies showing that depression during pregnancy is one of the strongest predictors of PPD.
While this study and many others have identified depression during pregnancy as a risk factor for PPD, we don’t know exactly how it contributes to the risk. Some have hypothesized that a dysfunction in the neuroendocrine system and vulnerability to changes in the hormonal environment may explain the link between antenatal depression and PPD. Another hypothesis is that depressive episodes during pregnancy may be associated with inflammation that increases vulnerability to postpartum stressors and subsequent depressive episodes. Another explanation is the “scar hypothesis.” It is thought that a depressive episode leads to permanent changes in personality, behavior and self-perception that make a person more vulnerable to depression in the future.
Questions remain. However, this study highlights the importance of screening for depression during pregnancy. Screening using standardized questionnaires represents an easy, low-cost means of identifying women at risk for PPD. Furthermore, the study shows that screening in the first trimester is just as important as screening in later trimesters. Furthermore, if we identify women with depressive symptoms during the first trimester, we have time to implement non-pharmacological and pharmacological interventions to address the current episode of depression and reduce the risk of PPD.
Ruta Nonacs, MD PhD
bibliographical references
Dlamini LP, Amelia VL, Shongwe MC, Chang PC, Chung MH. Antenatal depression across trimesters as a risk for postpartum depression and estimation of the fraction of postpartum depression attributable to antenatal depression: A systematic review and meta-analysis of cohort studies. Gen Hosp Psychiatry. 2023 November-December? 85:35-42.
