The role of social support in family socio-economic disparities in depressive symptoms during early pregnancy: Evidence from a Chinese birth cohort

Background: Few studies have examined the association between a composite measure of family socio-economic position (SEP)(2) and depressive symptoms among Chinese pregnant women, nor any potential underlying mechanisms which may be amenable to preventative interventions. Methods: We investigated the association between a composite SEP measure and depressive symptoms during early pregnancy, and tested for mediation by social support and moderation by parity in the Born in Guangzhou Cohort Study (n=12,382) using adjusted logistic regression and causal mediation analysis. Results: In this population, 18.4% of women experienced depressive symptoms before the 20th gestational week. Compared with the highest quartile, the lowest SEP score quartile was associated with a higher risk of depressive symptoms (OR 1.50, 95% CI 1.31-1.71), which was more pronounced among multiparous women than nulliparous women (P for interaction < 0.001). Social support mediated the association between SEP and depressive symptoms, with greater proportion mediated in nulliparous women (73.4% for the lowest SEP score quartile) than multiparous women (30.5%). Limitations: Depressive symptoms were measured by Self-rated Depression Scale, which is not designed as a clinical diagnosis tool for depression. We only had information on perceived social support but not actual social support, although these two parameters were modestly correlated. Conclusion: Lower SEP was associated with higher risk of depressive symptoms in pregnant women, driven by social support. And the association between SEP and depressive symptoms and mediation by social support were modified by parity. Whether this association extends to the post pregnancy period or is amenable to cost-effective interventions should be investigated in further studies.