Passive smoking and postpartum depression among Chinese women: A prospective cohort study in Tianjin, China.

Smoking has been associated with depression in the general population. Whether passive smoking is also associated with postpartum depression (PPD) is uncertain. From 2010 to 2012, we recruited 8,842 pregnant women in Tianjin, China. The mainland Chinese version of the Edinburgh Postnatal Depression Scale was used to evaluate postpartum depressive symptoms after birth, with a score of >9 defining PPD. Data were collected using specially designed questionnaires or data from the electronic database of Tianjin Maternal and Child Health Information System. Odds ratios (OR) and 95 percent confidence intervals (CI) were obtained for the association of smoking status with PPD using binary logistic regression. Passive smoke exposure rates before and during pregnancy were 40.9 percent and 52.1 percent, respectively. A total of 8.5% (n = 747) of participants had PPD. Compared with those not exposed, women passively exposed to smoke before and during pregnancy had higher odds of PPD (before pregnancy: OR: 1.24, 95 percent CI: 1.03-1.50; during pregnancy: OR: 1.43, 95 percent CI: 1.16-1.77) after adjustment for confounding factors. Passive smoking before and during pregnancy were associated with PPD in Chinese women. Reducing passive smoke exposure may reduce PPD in Chinese women; further longitudinal studies are warranted to replicate these findings.