Association between family members and risk of postpartum depression in Japan: Does "who they live with" matter? -The Japan environment and Children's study.

There are many psychosocial and biomedical risk factors for postpartum depression (PPD). However, associations between co-resident family members and PPD risk have not been examined. This study investigated whether co-resident family members were associated with risk for PPD during 1 month postpartum among Japanese women, and if these associations were modified by household income and their perceived partner's involvement in childcare. The sample comprised 86,490 women. Data were drawn from the Japan Environment and Children's Study, a large-scale national cohort study started in 2011. Our major predictor was co-resident family members when they registered around the first trimester of the women's pregnancy: partner, parent(s), parent(s)-in-law, or child(ren). The outcome was PPD at 1 month after delivery, assessed by the Edinburgh Postnatal Depression Scale. Adjusted odds ratios (OR) for family members and PPD incidence were calculated using multivariable logistic regression analysis. Subgroup analyses were conducted by household income and perceived partner's involvement in childcare. Adjusted ORs (95% confidence interval) for PPD for those not living with their partner, parent(s), parent(s)-in-law, or child(ren) compared with those who lived with these family members were 1.21 (1.07-1.37), 1.13 (1.03-1.24), 0.91 (0.84-0.98), and 1.42 (1.31-1.53), respectively. The level of perceived partner's involvement in childcare changed the identified association between family member and PPD. We found that "who a pregnant woman lives with" affects the risk of PPD in the first month postpartum, and high levels of perceived partner's involvement in childcare reduced harmful effects/increased protective effect of family members on PPD incidence. These findings suggested that interventions to increase perceived partner's support for childcare may be effective in preventing PPD, regardless of living situation.