1106: Can we define abnormal first stage of labor duration by maternal morbidity?

Abstract

Current guidelines for labor management do not define abnormal labor based on maternal morbidity. We aim to define abnormal duration of the first stage of term labor based on the risk of maternal morbidity. We conducted a secondary analysis of a single-center prospective cohort study of all consecutive women admitted for delivery at ≥37 0/7 weeks’ gestation with singleton, nonanomalous, vertex infants from 2010-2015 who reached 10cm cervical dilation. Multivariable logistic regression compared maternal outcomes among women above and below the 90th, 95th, and 97th percentiles for first stage of labor duration. Receiver-operator characteristic (ROC) curves estimated the association between first stage of labor duration and maternal morbidity. Maternal morbidity was a composite of postpartum fever, hemorrhage, transfusion or endomyometritis; prolonged second stage duration; and cesarean or operative vaginal delivery. Of 6,823 included women, 681 had first stage of labor duration above the 90th percentile, which was associated with an increased risk of composite maternal morbidity, postpartum fever or transfusion, prolonged second stage duration, and cesarean or operative vaginal delivery (p< 0.01). The odds of composite maternal morbidity; postpartum fever, hemorrhage or transfusion; prolonged second stage; and cesarean or operative vaginal delivery were significantly increased by 1.5-2.5 times among women above the 90th percentile for first stage of labor duration. ROC curves among all women from 3-10cm and 6-10cm, including when stratified by parity and type of labor onset, had an area under the curve of 0.51-0.62, demonstrating that duration of labor has moderate predictive ability, at best, for composite maternal morbidity. No curve demonstrated a clear point at which adverse maternal outcomes increased that could be used to define abnormal labor. The benefit of expectantly managing a prolonged first stage of labor with duration above the 90th percentile in anticipation of vaginal delivery must be weighed against the increased risk of maternal morbidity.View Large Image Figure ViewerDownload Hi-res image Download (PPT)