Impact of Interpregnancy Interval after Cesarean Section on Perinatal Outcomes in Multiparous Women of Advanced Maternal Age: A Retrospective Cohort Study

Background: This study aims to evaluate the impact of different interpregnancy intervals (IPIs) after a previous cesarean section on perinatal events in elderly multiparous women. Methods: In this retrospective cohort study, multiparous women of advanced maternal age who had a previous cesarean section between January 1, 2019, and December 31, 2019, were included.IPI was defined as the duration between live birth and subsequent conception.Multivariate logistic regression analysis was used to assess the association between variant IPIs (< 24 months, 60–119 months, and ≥ 120 months) and perinatal outcomes, with an IPI of 24–59 months as the reference group.The risks of anemia, gestational hypertension, gestational diabetes mellitus,placenta previa,premature rupture of membrane,uterine rupture and successful vaginal were compared among the 4 groups. Results: We recorded a total of 591 births following cesarean delivery: 16, 89, 290, and 196 births in the IPI < 24 months, 24–59 months, 60–119 months, and ≥ 120 months groups, respectively.Women with an IPI of ≥ 120 months had a significantly higher incidence of gestational hypertension (6.1%, p<0.001) than the other three groups. In women with a prior cesarean delivery and an IPI< 24 months, there was an increased risk of incomplete uterine rupture (OR 1.89, 95% CI 1.13–1.87) and low 1-minute Apgar scores (OR 1.55, 95% CI 0.45–4.63). The IPI did not impact the occurrence of incomplete uterine rupture in women with a history of emergency cesarean section.There was no significant association between the IPI and other adverse perinatal outcomes, such as anemia ,gestational diabetes mellitus,abnormal placental position, pernicious placenta, placenta accreta, placental abruption, postpartum hemorrhage, hysterectomy, or neonatal intensive care admission.An IPI < 24 months was associated with higher likelihood of premature rupture (OR 1.97, 95%CI 0.58–10.2). Conclusion: Women with an IPI of ≥ 120 months had a higher rate of gestational hypertension compared to the other groups, while an IPI of < 24 months increased the risk of incomplete uterine rupture and low 1-minute Apgar scores.