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.