Association between incense burning and prenatal depressive symptoms: evidence from the Born in Guangzhou Cohort Study

This study aimed to examine the association of incense burning alone, a source of indoor air pollution, and jointly with passive smoking, with prenatal depressive symptoms. Information on incense exposure and depressive symptoms were collected at both early and late pregnancy using questionnaires in the Born in Guangzhou Cohort Study. Mixed-effects logistic regression models were used to assess the associations of incense exposure separately, and together with passive smoking, with prenatal depressive symptoms. Compared to the non-users, pregnant women with household incense burning had higher odds of depressive symptoms (odds ratio (OR), 1.17, 95% CI, 1.06, 1.28). Compared with non-users, women who occasionally (OR, 1.22, 95% CI, 1.09, 1.36) and frequently (1.51, 95% CI, 1.26, 1.80) smelled incense had higher odds of prenatal depressive symptoms. Higher duration of incense smelling was associated with higher odds of prenatal depressive symptoms compared with non-users. There was no strong evidence for an interaction of frequency of incense smelling and passive smoking in prenatal depressive symptoms. Prenatal exposure to incense burning was associated with higher odds of having depressive symptoms during pregnancy, and there is no evidence for interaction with concurrent exposure to passive smoking.