The association between a history of induced abortion for nonmedical reasons and maternal and neonatal perinatal outcomes: a retrospective cohort study

Introduction Following the implementation of the universal two-child policy in China, many multiparous women who had a history of induced abortion gave birth again. However, there is a lack of studies exploring the associations between induced abortion for nonmedical reasons and maternal and neonatal perinatal complications. Methods In this retrospective cohort study, the participants were multiparous women who gave birth to singleton babies at or after 28 weeks of gestation between 1 December 2015, and 1 December 2020. The exposure factor was a maternal history of induced abortion for nonmedical reasons. Logistic regression models were used to adjust for potential confounding factors, and adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated for maternal and neonatal perinatal outcomes. The dose-effect relationships between the number of induced abortions for nonmedical reasons and adverse outcomes were tested by the Cochran-Armitage trend test (p for trend). Stratified analyses were conducted to test the robustness of the results in subgroups with different maternal ages or interpregnancy intervals. Results There were 3985 multiparous women with a history of induced abortion for nonmedical reasons and 1823 multiparous women without such a history. Compared to women without such a history, women with a history of induced abortion for nonmedical reasons had increased risks of cesarean section (adjusted OR, 1.44; 95% CI: 1.23 - 1.69), placenta-related complications (adjusted OR, 2.14; 95% CI: 1.68 - 2.72), uterine-related complications (adjusted OR, 1.24; 95% CI: 0.97 - 1.59), HDP (adjusted OR, 1.49; 95% CI: 1.16 - 1.93), and preterm birth (adjusted OR, 1.24; 95% CI: 1.05 - 1.48) in subsequent pregnancy. In addition, there were dose-effect relationships between the number of induced abortions and the number of cesarean sections (P-trend <.001), placenta-related complications (P (trend) <.001), uterine-related complications (P-trend =.016), HDP (P-trend =.0003), and preterm birth (P (trend) =.0006). Similar trends were observed in most subgroups with different maternal ages or interpregnancy intervals. Conclusions A history of induced abortion for nonmedical reasons was associated with increased risks of maternal and neonatal perinatal complications. Furthermore, dose-effect relationships were observed for these associations.