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749: Factors influencing the rate of uterine rupture during a trial of labor after cesarean: a 2012-2015 national cohort

      Objective

      Uterine rupture during a trial of labor (TOL) after cesarean (CD) can result in serious maternal and fetal morbidity. We sought to identify factors associated with uterine rupture during a TOL among a contemporary cohort.

      Study Design

      This is a retrospective cohort study of term, non-anomalous, singleton, vertex pregnancies attempting a TOL following a previous cesarean in the United States from 2012-2015. Maternal factors (age, education, marital or insurance status, smoking, race, weight, weight gain, history of previous vaginal delivery, number of previous cesareans, medical co-morbidities), intrapartum factors (induction of labor (IOL), gestational age), and fetal weight were then analyzed using chi-squared tests. A multivariate logistic regression model was then used to explore the factors associated with uterine rupture during a TOL.

      Results

      There were 1,767,305 women with a history of 1 or 2 CD in our cohort, and 305,132 (17.3%) underwent a TOL. For those undergoing a TOL, 647 (0.21%) uterine ruptures occurred.
      There were 1,332,513 women with 1 previous CD, 274,418 (20.5%) attempted a TOL, and 579 (0.21%) uterine ruptures occurred. In multivariate analysis, IOL was the strongest predictor of uterine rupture, while a history of previous vaginal delivery was the most predictive (Table). Gestational age at or beyond 40 weeks was associated with uterine rupture even when controlling for IOL. There were 434,792 women with 2 previous CD, 30,714 (7.1%) attempted a TOL, and 68 (0.22%) uterine ruptures occurred. In multivariate analysis, only a previous vaginal delivery was associated with uterine rupture.

      Conclusion

      In a large retrospective cohort, maternal age, American Indian/Alaskan Native race, diabetes mellitus, gestational hypertension, and gestational age 40 weeks or greater were associated with uterine rupture during a TOL following 1 CD, while Hispanic ethnicity and a history of previous vaginal delivery were protective. These data can be used to counsel women considering a TOL.
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