230: Induction of labor and cesarean delivery by gestational age

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ObjectiveOften, studies of cesarean delivery rates among women undergoing induction of labor compare such women to those experiencing spontaneous labor at the same gestational age. However, in a randomized trial, induction of labor is compared to expectant management, and thus, increasing gestational age. We sought to examine the association between induction of labor and cesarean delivery, accounting for the effect of increasing gestational age in expectant management.Study DesignWe conducted a retrospective cohort study of all term, singleton, deliveries in the United States in 2003. Exclusion criteria were placenta previa, breech presentation, diabetes and a prior cesarean delivery. For each gestational age, women undergoing induction (IOL), were compared to a group of women who were undelivered at that gestational age, and who experienced labor at some future gestational age (Expt Mgmt).ResultsIn nulliparous women undergoing induction of labor at 38 weeks gestation, the cesarean delivery rate was 23.3% as compared to 24.4% (p<0.001) of women beyond 38 weeks gestation. At 39 and 40 weeks of gestation, there were similar decreases in the cesarean delivery rate in the induced group. However, at 41 weeks there was no statistically significant difference between the two groups (p=0.255). These findings persisted among multiparous women and when controlling for potential confounders.ConclusionTabled 1Induction of Labor Compared to Delivery at a Greater Gestational AgeWk of IOLIOL CDExpt Mgmt CDp-value38wks23.3%24.4%<0.00139wks24.3%25.8%<0.00140wks28.4%30.4%<0.00141wks33.4%32.9%0.255 Open table in a new tab ObjectiveOften, studies of cesarean delivery rates among women undergoing induction of labor compare such women to those experiencing spontaneous labor at the same gestational age. However, in a randomized trial, induction of labor is compared to expectant management, and thus, increasing gestational age. We sought to examine the association between induction of labor and cesarean delivery, accounting for the effect of increasing gestational age in expectant management. Often, studies of cesarean delivery rates among women undergoing induction of labor compare such women to those experiencing spontaneous labor at the same gestational age. However, in a randomized trial, induction of labor is compared to expectant management, and thus, increasing gestational age. We sought to examine the association between induction of labor and cesarean delivery, accounting for the effect of increasing gestational age in expectant management. Study DesignWe conducted a retrospective cohort study of all term, singleton, deliveries in the United States in 2003. Exclusion criteria were placenta previa, breech presentation, diabetes and a prior cesarean delivery. For each gestational age, women undergoing induction (IOL), were compared to a group of women who were undelivered at that gestational age, and who experienced labor at some future gestational age (Expt Mgmt). We conducted a retrospective cohort study of all term, singleton, deliveries in the United States in 2003. Exclusion criteria were placenta previa, breech presentation, diabetes and a prior cesarean delivery. For each gestational age, women undergoing induction (IOL), were compared to a group of women who were undelivered at that gestational age, and who experienced labor at some future gestational age (Expt Mgmt). ResultsIn nulliparous women undergoing induction of labor at 38 weeks gestation, the cesarean delivery rate was 23.3% as compared to 24.4% (p<0.001) of women beyond 38 weeks gestation. At 39 and 40 weeks of gestation, there were similar decreases in the cesarean delivery rate in the induced group. However, at 41 weeks there was no statistically significant difference between the two groups (p=0.255). These findings persisted among multiparous women and when controlling for potential confounders. In nulliparous women undergoing induction of labor at 38 weeks gestation, the cesarean delivery rate was 23.3% as compared to 24.4% (p<0.001) of women beyond 38 weeks gestation. At 39 and 40 weeks of gestation, there were similar decreases in the cesarean delivery rate in the induced group. However, at 41 weeks there was no statistically significant difference between the two groups (p=0.255). These findings persisted among multiparous women and when controlling for potential confounders. ConclusionTabled 1Induction of Labor Compared to Delivery at a Greater Gestational AgeWk of IOLIOL CDExpt Mgmt CDp-value38wks23.3%24.4%<0.00139wks24.3%25.8%<0.00140wks28.4%30.4%<0.00141wks33.4%32.9%0.255 Open table in a new tab