The Influence of Interpregnancy Interval on Maternal Complications and Pregnancy Outcomes After Prior Cesarean: A Retrospective Cohort Study

Background: The interpregnancy interval (IPI) is a significant factor influencing pregnancy outcomes, particularly in women with a prior cesarean section. Understanding how IPI influences maternal complications and pregnancy outcomes is crucial for guiding post-cesarean pregnancy management. Methods: A retrospective cohort study was conducted on 1803 women who underwent cesarean delivery at Guangzhou Women and Children’s Medical Center between January 1, 2011, and June 30, 2022. Those with a first cesarean delivery followed by one or more subsequent births were included. Participants were assigned into four IPI-based groups for comparison. Data of clinical characteristics (including age, marital status, mode of delivery, newborn weight, and medical history), maternal complications [including gestational diabetes mellitus (GDM), gestational hypertension, preeclampsia, polyhydramnios, oligohydramnios, placenta accreta, and placenta previa], and pregnancy outcomes [including fetal distress, macrosomia, postpartum hemorrhage, premature rupture of membranes (PROM), and preterm birth] were collected and analyzed using univariate and multivariate logistic regression. Results: Significant differences in clinical characteristics and maternal complications were observed across the IPI groups after cesarean section. Women with IPIs of ≥60 months had the highest mean age (34.09 ± 2.92, p < 0.001) and increased risks of GDM (26.04%, p = 0.021) and placenta accreta (7.29%, p = 0.010). The IPI group of <18 months exhibited the highest rates of gestational hypertension (15.15%) and oligohydramnios (4.55%). Significant associations between IPI and adverse pregnancy outcomes, such as fetal distress and PROM, were observed, particularly at the extremes of IPI (<18 months and ≥60 months). After adjusting for potential confounding factors, including age and history of gestational hypertension, preeclampsia, postpartum hemorrhage, macrosomia, placenta previa, and fetal distress, multivariate logistic regression analysis revealed that the risk of GDM was significantly reduced in the 18–23 months IPI group compared to the 24–59 month group [adjusted odds ratio (OR) = 0.630; 95% confidence interval (CI): 0.431–0.920; p < 0.017]. Gestational hypertension was strongly associated with shorter IPIs, whereas preeclampsia and placenta accreta were more common with longer IPIs. The risk of PROM increased with both very short and very long IPIs. Postpartum hemorrhage was more frequent in the 18–23 months group, and preterm birth risk increased significantly with IPIs of ≥60 months. Conclusion: Both short and long IPIs following a cesarean section are associated with specific adverse maternal complications and pregnancy outcomes. Individualized counseling and planning for subsequent pregnancies may benefit women with a history of cesarean delivery to minimize these risks.