Abstract Background Unintended (unwanted) pregnancy is a sexual and reproductive health issue with psychosocial consequences for the individual, their family, and society. However, the relationship between social support and related mental health issues, like depression and the effects of childhood adversity, is poorly studied. This study aims to explore the connections between childhood adversity, perceived social support, and depressive symptoms in pre-abortion women (women who have decided to have an abortion) in a clinical setting, based on the common risk factor approach and social support theory. Methods A total of 299 pre-abortion Chinese women 18–45 years were recruited in a hospital in Shantou, China. Hierarchical linear regression analyses were employed to examine the relative effects of childhood adversity and sources of social support on depressive symptoms, controlling for sociodemographic influences. Results The results show that 37.2 percent of participants reported at least one adverse experience in childhood. More than half of the respondents were at risk for depression. Results of regression analysis showed that childhood adversities were negatively associated with depressive symptoms before sources of social support were entered into the model. However, when the sources of perceived social support were added, the effect of childhood adversity was not significant. Perceived social support explained the additional 15 percent variance in depressive symptoms. Additionally, being married (β = -.12, p