Weight-loss behaviors before pregnancy associate with increased risk of postpartum depression from the Japan Environment and Children's Study.

No studies showed the association between weight-loss behaviors before pregnancy and postpartum depression (PPD). We analyzed data from the nation-wide birth cohort study, the Japan Environment and Children's Study. Self-administrated questionnaires answered by 62,446 women was analyzed using logistic regression analysis. PPD was assessed using the Edinburgh Postnatal Depression Scale at 1 month after delivery. Women using at least one weight-loss method had higher risk of PPD than women using no weight-loss methods [women without antenatal psychological distress according to Kessler 6-Item Psychological Distress score: adjusted odds ratio (aOR) 1.318, 95% confidence interval (CI) 1.246-1.394; women with antenatal psychological distress: aOR 1.250, 95% CI 0.999-1.565]. Using extremely unhealthy weight-loss methods was associated with PPD compared with no use of each weight-loss method (vomiting after eating: aOR 1.743, 95% CI 1.465-2.065; smoking: aOR 1.432, 95% CI 1.287-1.591; taking diet pills: aOR 1.308, 95% CI 1.122-1.520). The association between weight-loss behaviors and PPD varied according to pre-pregnancy BMI. In normal-weight women, the weight-loss method score, which indicates the degree of weight-loss method use, was associated with PPD. These results indicate using weight-loss methods before pregnancy is associated with an increased risk of PPD in Japanese women.