Shoulder Dystocia and Composite Adverse Outcomes for the Maternal-Neonatal Dyad.

BACKGROUND While the neonatal morbidity associated with shoulder dystocia are well known, the maternal morbidity occurring with this obsetetric emergency is infrequently reported. OBJECTIVE To assess the composite maternal and neonatal adverse outcomes among vaginal deliveries (at 34 weeks or later) with and without shoulder dystocia. MATERIAL AND METHODS This is a secondary analysis of Consortium of Safe Labor, an observational obstetrical cohort of all deliveries occurring at 19 hospitals (from 2002-2008) who delivered vaginally and had data on the occurrence of shoulder dystocia. The composite maternal adverse outcome included 3rd or 4th degree perineal laceration, postpartum hemorrhage (>500 cc blood loss for a vaginal delivery and >1000 cc blood loss for cesarean section), blood transfusion, chorioamnionitis, endometritis, thromboembolism, admission to intensive care unit, or maternal death. The composite neonatal adverse outcome included Apgar score < 7 at 5 min, birth injury, neonatal seizure, hypoxic ischemic encephalopathy, or neonatal death. Multivariable Poisson regression was used to estimate adjusted relative risks (aRR) with 95% confidence intervals (CI). Area under the receiver operating characteristic curve (AUC) was constructed to determine if clinical factors would identify shoulder dystocia. RESULTS Of the 228,438 women in the overall cohort, 130,008 (59.6%) met the inclusion criteria, and among them shoulder dystocia was documented in 2,159 (1.7%) cases. The rate of composite maternal morbidity was significantly higher among deliveries with shoulder dystocia (14.7%) than without (8.6%; aRR 1.71, 95% CI 1.64-2.01). The most common maternal morbidity with shoulder dystocia was 3rd or 4th degree laceration (aRR 2.82; 95% CI 2.39-3.31). The risk of the composite neonatal morbidity with shoulder dystocia (12.2%) was also significantly higher than without (2.4%; aRR 5.18, 95% CI 4.60-5.84). The most common neonatal morbidity was birth injury (aRR 5.39, 95% CI 4.71-6.17). AUC for maternal characteristic to identify shoulder dystocia was 0.66 and 0.67 for intrapartum factors. CONCLUSIONS Though shoulder dystocia is unpredictable, the associated morbidity affects both mothers and newborns. Focus should be on concurrently averting the composite morbidity for the maternal-neonatal dyad with shoulder dystocia.