The impact of length of second stage of labor on shoulder dystocia outcomes: a retrospective cohort study

Abstract

To compare obstetrical and neonatal outcomes of vaginal deliveries complicated by shoulder dystocia, according to the length of second stage of labor. We conducted a retrospective cohort study of 177 shoulder dystocia cases that were divided into three categories according to second stage duration (1-20, 21-59, 60-180 min, respectively). The three categories were compared in terms of obstetric characteristics and neonatal outcomes. Statistical analysis utilized the χ2-test and analysis of variance where appropriate. The odds ratios of brachial plexus injury and having a 5-min APGAR score <7 across the second stage duration categories were calculated using logistic regression models that adjusted for potential confounders. The incidence of brachial plexus injury was 5.4% (1st category), 4.4% (2nd category) and 26.9% (3rd category); P<0.01. The higher incidence of brachial plexus injury in the group where second stage lasted >1 h was confirmed by logistic regression, with and without adjusting for confounders. The incidence of brachial plexus injury increases with the length of second stage, even after controlling for confounders.