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23: Factors associated with adverse outcomes in nulliparas at 39 weeks with induction or expectant management

      Objective

      To evaluate the association between baseline patient characteristics and adverse outcomes in low-risk nulliparous women randomized to planned induction of labor (IOL) at 39 weeks or expectant management (EM).

      Study Design

      A secondary analysis of women randomized at 38 weeks to IOL at 39 weeks or EM, and delivered at ≥39 weeks. Eligibility for this analysis is defined in the table footnote. Outcomes evaluated included a composite of perinatal death or severe neonatal complications, 3rd/4th degree perineal lacerations, and postpartum hemorrhage (PPH) (Table). Log binomial multivariable models were used to estimate relative risk (RR) of outcomes associated with maternal age, race/ethnicity, body mass index (BMI) and modified Bishop score at randomization, marital and employment status, insurance, smoking, drinking, prior pregnancy loss (<20 weeks), assisted conception, and treatment group. Additional models evaluated interaction between significant characteristics and treatment group.

      Results

      Of 6106 women enrolled in the trial 5,147 remained eligible for inclusion in this analysis. The perinatal composite outcome occurred in 108 (4.2%) women in the IOL group and 151 (5.9%) women in the EM group (p=0.007). Frequencies of 3rd or 4th degree perineal laceration and PPH were similar between IOL and EM groups (laceration: 3.5% vs. 3.1%, p=0.46; PPH: 4.9% vs. 4.7%, p=0.67). In multivariable regression, the only characteristics significantly associated with an increased risk of the perinatal composite outcome were increasing BMI and EM (Table). A decreased risk of 3rd/4th degree perineal laceration was observed with increasing BMI and in black women, and an increased risk observed in Asian women (vs. white women). An increased risk of PPH was observed in Hispanic women (vs. white women). None of associations between patient characteristics and outcomes varied significantly by treatment group.

      Conclusion

      Among women eligible for this analysis, only EM and increasing BMI were significantly associated with the perinatal composite, while race/ethnicity was significantly associated with both 3rd/4th degree lacerations and PPH. Of patient characteristics evaluated, none identified a sub-group of women more likely to have adverse outcomes with IOL.
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