Association between route of delivery and maternal adverse outcomes in pregnancies complicated by preterm birth.

ABSTRACT

INTRODUCTION: To determine the impact of route of delivery on maternal outcomes among individuals who deliver preterm (before 37 weeks). MATERIALS AND METHODS: This was a population-based retrospective cohort study using the U.S. vital statistics datasets on Period Linked Birth-Infant Death Data from 2014 to 2018. The study population was restricted to live births from women with non-anomalous singletons who delivered at 24-36 weeks of gestation. The main explanatory variable for this study was route of delivery, which was categorized as (i) vaginal delivery, (ii) cesarean delivery with labor, and (iii) cesarean delivery without labor. The primary outcome was composite maternal adverse outcome, which encompassed any of the following admission to the intensive care unit, maternal blood transfusion, uterine rupture, or unplanned hysterectomy. The results were presented as adjusted relative risk (aRR) with 95% confidence interval (CI). RESULTS: Over the study period 1,440,510 live births met the inclusion criteria, and the overall composite maternal adverse outcome was 14.38 per 1,000 live births. After multivariable adjustment, compared to women who underwent a vaginal delivery, the risk of composite maternal adverse outcome was higher in women who had a cesarean delivery with labor (aRR 3.70; 95% CI 3.52-3.90) and those who had a cesarean delivery without labor (aRR 4.79; 95% CI 4.59-4.98). CONCLUSION: With preterm birth, cesarean delivery without labor has higher rate of composite maternal morbidity than cesarean during labor or vaginal delivery.