Stage-specific association between unintended pregnancy and perinatal depression and the modifying roles of socioeconomic status: A longitudinal cohort study in China.

Objectives: To prospectively examine the stage-specific association between unintended pregnancy and perinatal depressive (PND) symptoms across pregnancy and postpartum, and to explore the moderating influence of socioeconomic status (SES) in this dynamic in a Chinese cohort.

Methods: Utilizing data from the Chinese Pregnant Women Cohort Study-Peking Union Medical College (CPWCS-PUMC), a multicenter prospective cohort of 9134 participants, depressive symptoms were assessed using the Edinburgh Postnatal Depression Scale (EPDS) at four time points. Generalized estimating equations (GEE) with autocorrelation working correlation matrices evaluated associations, adjusting for sociodemographic, health-risk behavioral, and obstetric confounders. Subgroup analyses stratified by SES indicators (education level, employment status, and income) were conducted to explore heterogeneity.

Results: A total of 9134 participants were included, with 29.17 % (2664/9134) classified as unintended pregnancies. Women with unintended pregnancies were about 1.27 times (aOR = 1.27, 95 % CI: 1.17-1.39, p < 0.001) more likely to suffer from PND, with risk peaking in the third trimester (aOR = 1.50, 95 % CI: 1.28-1.75, p < 0.001). No significant association was observed postpartum (aOR = 1.12, 95 % CI: 0.86-1.45, p = 0.382). Subgroup analyses revealed amplified risks of depression in the third trimester among low-SES populations. Women with ≤ middle school education level (aOR = 1.76, 95 % CI: 1.18-2.63, p = 0.006) and those in the lowest income quintile (aOR = 1.89, 95 % CI: 1.33-2.68, p < 0.001) showed significantly higher third-trimester risks.

Conclusions: Unintended pregnancy is an independent risk factor for PND, particularly during late pregnancy, with SES exacerbating this association. These findings underscore the need for universal contraception education and pregnancy intention screening, as well as mental health interventions targeting low SES populations.