Prenatal depression increases the odds of preterm birth in a prospective cohort study in Hangzhou

There is little evidence about the susceptible exposure window of maternal depression during pregnancy and preterm birth in China. We aimed to assess the trimester-specific association of depression during pregnancy with preterm birth, and the effect modification of social support. In 2021–2023, a prospective cohort study was conducted in Hangzhou, China. Depression was measured using the Edinburgh Postnatal Depression Scale (EPDS) during three trimesters of pregnancy. The Social Support Rating Scale (SSRS) and Life Events Scale for Pregnant Women (LESPW) were adopted to evaluate the social support and stress exposure of pregnant women. Binary logistic regression models were used to evaluate the associations of SSRS, LESPW, and EPDS with preterm birth, presenting as odds ratio (OR) and 95% confidence interval (CI). Stratified analysis by SSRS was performed. Of 3692 pregnant women, 190 (5.1%) had a preterm birth, and the prevalence of depression was 12.1%, 10.2%, and 7.4% for the 1st, 2nd, and 3rd trimester, respectively. High EPDS in the 1st trimester contributed to an increased OR of preterm birth (1.60, 95% CI 1.03, 2.40) after adjusting for potential confounders. Although stratified analyses suggested a significant association only among women with low social support (1.58, 95% CI 1.00, 2.50), the formal interaction test was not significant. Maternal depression during the first trimester seemed to elevate the odds of preterm birth. The association was not modified by social support in our study. It is recommended to establish an early screening system for depression during pregnancy and seek professional psychological counseling and treatment when necessary, to reduce the risk of preterm birth.