The Effects of Birth Spacing After Cesarean Delivery on Pregnancy Outcomes: A Retrospective Cohort Study

The changing family planning policy from One-Child to Two-Child Policy, led to a significant increase in the proportion of pregnancies with variant interpregnancy intervals (IPIs) after previous cesarean section (CS). To examine the relationship between IPI and perinatal outcomes, we conducted a retrospective cohort study of 1854 women having a history of CS and delivered in 2016 at West China Second University Hospital. With an IPI of 24-59 months as the reference, the associations between various IPIs (<24, 60-119, and ≥120 months) and pregnancy outcomes were examined by multivariate logistic regression analysis with multiple models. We found that IPI <24 months significantly increased the risk of anemia in late pregnancy (aOR 2.09, 95% CI 1.21-2.62, p = 0.008). IPI <24 months was associated with a higher risk for incomplete uterine rupture (OR 1.30, 95% CI 1.05-1.61), IPI ≥60 months was related to a lower risk for incomplete uterine rupture (IPI = 60-119 months: OR 0.77, 95% CI 0.62-0.95; IPI ≥120 months, OR 0.59, 95% CI 0.38-1.08), and women with IPI ≥120 months were more likely to develop gestational hypertension (GHP) (p = 0.036) and gestational diabetes mellitus (GDM) (p = 0.001). These effects became nonsignificant after adjusting possible confounders. This study revealed that IPI may combine with other factors to affect GHP, GDM, and uterine rupture in the subsequent pregnancy after previous CS.