(771) Outcomes in Vaginal versus Cesarean Periviable Breech Delivery: A 5-year, Propensity Score–Matched Study

Objective: To determine maternal and neonatal outcomes associated with vaginal versus cesarean breech delivery at periviability.

Study Design: This study analyzed non-anomalous, singleton, breech live births at 22w0d to 25w6d gestational age identified in the CDC Linked Birth/Infant Death Records data from 2016 to 2021. Multiple imputation was used to account for missing data. A propensity score (PS) analysis was conducted to establish pseudo-randomization based on the mode of delivery matching vaginal to cesarean deliveries at a ratio of 1:2 using greedy nearest-neighbor matching. The balance diagnostic was measured using standardized mean difference. In the outcome model, we estimated the risk difference (RD) and risk ratios (RR) and associated 95% CIs based on generalized estimation equation framework, using log-linear models with binomial distribution and a log/ identity link, respectively, after re-adjusting for gestational age (GA).

Results: Of 21,461 periviable breech singleton births, 34% (N= 7,289) delivered vaginally. Vaginal delivery was more common in earlier GA. After PS matching, the distributions of baseline factors were balanced between the delivery arms. A composite of adverse neonatal outcomes occurred among 99.0% (N = 7,213) of vaginal and 96.8% (N = 13,716) of cesarean breech births (RD 1.85, 95% CI -1.77 to 5.46; RR 1.02, 95% CI 0.98 to 1.06). Neonatal mortality was significantly higher for vaginal than cesarean breech births (73% versus 36%; RD 28.29 95% CI 25.50 to 31.07; RR 1.70, 95% CI 1.61 to 1.79). A composite of adverse maternal outcomes occurred in 1.6% of vaginal breech and 3.1% of cesarean births (RD -1.58, 95% CI -2.20 to -0.96, RR 0.48, 95% CI 0.36 to 0.65).

Conclusion:

Vaginal breech birth between 22w0d and 25w6d gestation is associated with lower risk of adverse maternal outcomes but higher risk of neonatal mortality.