LAUSR

INTRODUCTION Previous studies in Western countries have examined the association between prenatal smoking and risk for Postpartum depression (PPD). However, evidence from Japan is lacking, despite the high prevalence of smoking among pregnant women. Therefore, we examined the association between prenatal smoking and PPD among pregnant Japanese women. METHODS We analyzed data for up to 1 month after childbirth from the Japan Environment and Children's Study (JECS), a nationwide birth cohort study. Among the 103,070 pregnant women recruited, 80,872 eligible participants were included in the analysis. PPD was defined as a score of ≥9 on the Edinburgh Postnatal Depression Scale (EPDS). Prenatal smoking and length of smoking cessation among ex-smokers were obtained using self-administered questionnaires at second/third trimester. RESULTS Among 80,872 pregnant women, 9.0% reported PPD. Multivariable-adjusted odds ratios (OR) (95% confidence intervals) for PPD (reference: never smoked) were 1.24 (1.12-1.37) for women who quit smoking after becoming pregnant, and 1.38 (1.21-1.56) for those who smoked during pregnancy. Compared with women who had never smoked, those who quit smoking ≤5 years before childbirth had a higher occurrence of PPD, with a multivariable-adjusted OR of 1.10 (1.00-1.22). LIMITATIONS Questionnaire data was self-reported by participants, thus smoking status might be under-reported. CONCLUSIONS Women who smoked during pregnancy, quit smoking after becoming pregnant, and quit smoking ≤5 years before childbirth are more likely to experience PPD than those who had never smoked.