Association between gestational age at planned repeat cesarean delivery and uterine scar dehiscence

To evaluate the association between gestational age at planned repeat cesarean delivery and intraoperatively diagnosed uterine scar dehiscence (USD), and to assess gestational age–specific neonatal outcomes. This retrospective cohort study included women with at least one previous cesarean delivery who underwent pre-labor planned repeat cesarean delivery between 38 + 3 and 39 + 3 weeks of gestation from 2019 to 2025. Gestational age was categorized as 38 + 3 to 38 + 4, 38 + 5 to 39 + 0, and 39 + 1 to 39 + 3 weeks. The primary outcome was intraoperatively diagnosed USD. Multivariable logistic regression was performed in the full cohort, and propensity score matching was used as a sensitivity analysis. Among 1,104 women, 184 had intraoperatively diagnosed USD. Delivery at 39 + 1 to 39 + 3 weeks was associated with higher odds of USD compared with 38 + 5 to 39 + 0 weeks (adjusted odds ratio [aOR]: 3.53; 95% confidence interval [CI]: 2.47–5.04; p < 0.001), whereas delivery at 38 + 3 to 38 + 4 weeks was not (aOR: 0.92; 95% CI 0.58–1.45; p = 0.720). Neonatal outcomes were presented descriptively and were underpowered for multivariable adjustment. Previous cesarean delivery ≥ 2 (aOR: 5.20; 95% CI 3.47–7.79), interdelivery interval ≤ 2 years (aOR: 2.85; 95% CI 1.80–4.50), and antenatal suspected macrosomia (aOR: 2.24; 95% CI 1.34–3.73) were independently associated with USD. The matched sensitivity analysis showed consistent findings. Delivery at 39 + 1 to 39 + 3 weeks was associated with higher odds of intraoperatively diagnosed USD than delivery at 38 + 5 to 39 + 0 weeks. Previous cesarean delivery ≥ 2, interdelivery interval ≤ 2 years, and antenatal suspected macrosomia were independently associated with USD.