Early risk factors for postpartum depression: A longitudinal Japanese population-based study

Postpartum depression (PPD) negatively impacts maternal health, parenting and development of children. Most previous studies on PPD risk factors are based on Western populations. Additionally, little is known about the association between psychosocial factors during early pregnancy period and PPD. We aimed to identify early risk factors for PPD until three months after delivery using a longitudinal population-based sample from Japan.

The data was collected from 1050 mothers at four time points: first trimester, after the birth, and one and three months post-delivery. Mothers who had a Japanese Edinburgh Postnatal Depression Scale (EPDS) cutoff score above 9 at one or 3 months after delivery were recognized as having PPD (n = 91/8.7%).

Negative feelings about pregnancy, combined breast and bottle feeding, first-time motherhood, motherhood 24 or less years old, perceived maternal mental illness before pregnancy, and lack of social support were all significantly associated with PPD at three months after delivery.

The data was collected from one city in Japan, which limits the generalization of the findings. Additionally, PPD was assessed by an EPDS questionnaire, and not by a clinical interview.

Even after controlling for the perceived mental illness before pregnancy, several risk factors as early as in the first trimester were associated with PPD. These risk factors should be identified and the mothers should be offered a suitable intervention, in order to prevent the development of PPD.