A Cross-Sectional Study on the Association Between Abortion and Bipolar Disorder, Major Depression: Evidence from the UK Biobank.

BACKGROUND: Spontaneous and induced abortion are common reproductive events. Limited research has investigated the association between abortion and women's mental health, particularly bipolar disorder and major depression (BDMD). This study aims to explore this association to offer theoretical insights into women's health. METHODS: A cross-sectional analysis was conducted using data from 21,196 female participants in the UK Biobank. Participants were divided into four groups: no abortion history, spontaneous abortion only, induced abortion only, and both spontaneous and induced abortions. Inverse probability of treatment weighting (IPTW) was applied to reduce biases in treatment assignment. Logistic regression was used to examine the relationship between abortion and BDMD, while restricted cubic spline regression was employed to explore the nonlinear association between the number of abortions and BDMD. RESULTS: Among the 21,196 ever-gravid women, 10,583 (49.93%) experienced spontaneous abortion only, 7106 (33.53%) experienced induced abortion only, and 2804 (13.23%) experienced both spontaneous and induced abortions. The IPTW-multivariate logistic regression analysis showed that induced abortion only and both spontaneous and induced abortions were associated with BDMD, with adjusted odds ratios (ORs) of 1.18 (95% CI: 1.11-1.23) and 1.33 (95% CI: 1.27-1.39), respectively. Spontaneous abortion alone was not associated with BDMD, with an OR of 1.03 (95% CI: 0.98-1.08). A nonlinear association was identified between the number of abortions and BDMD. CONCLUSION: This study found that a history of abortion is linked to a higher risk of BDMD. Additional research is required to better understand this relationship and to offer theoretical insights for women's reproductive health.