Cesarean section in the second stage of labor is associated with early-term and late preterm birth in subsequent pregnancies.

Objectives: The objectives of this study were to determine in a population-based cohort study the association between cesarean section (CS) during the second stage of labor and the risk for preterm birth and/or cervical insufficiency in the subsequent pregnancy; to identify maternal and neonatal risk factors for long-term complications following CS due to prolonged second stage of labor.

Methods: We conducted a retrospective population-based cohort study including women who had at least one consecutive delivery following a CS at our institution from 1991 to 2018, provided that the first delivery was at term. We divided the study cohort into two groups: (1) women who delivered by CS due to failure to progress during the first stage of labor ( = 1068); and (2) those who delivered by CS due to arrest of descent at the second stage of labor ( = 603).

Results: Of the 120,147 women who met the inclusion criteria, 78,407 had a subsequent delivery during the study period. Women of group 1 were significantly older than those of group 2 ( = .018), and had a higher rate of assisted reproductive technology [61 (5.7%) vs. 18 (3.1%),  < .022,]. Additionally, their hospitalization period was significantly longer ( < .001). The rate of preterm birth in the subsequent delivery was higher among women who had a CS due to arrest of descent than those who had a CS due to arrest in dilatation [43 (7.3%) vs 49 (4.6%),  < .026]. This was confirmed after adjusting for confounding factors In a multivariable regression analysis (OR 1.78, 95% CI 1.14-2.76, value = .011) A Cox regression analysis implying gestational age at delivery at the time factor identifies CS due to arrest of descent as a risk factor for subsequent preterm birth (Hazard ratio 1.19 95% CI 1.07-1.31).

Conclusion: CS due to arrest of descent is an independent risk factor for subsequent preterm birth. The exact mechanisms contributing to this association are yet to be determined.

Synopsis: Cesarean section during the second stage of labor is an independent risk factor for late preterm birth in the subsequent pregnancy when compared to cesarean section in the first stage of labor.