Propranolol Rescue of Prolonged Labor

Inclusion Criteria: English-speaking \>= 36 weeks gestation Singleton pregnancy Vertex presentation No contraindication to a vaginal delivery Meets at least one study criteria for prolonged labor: 1. cervical dilation \<6 cm after ≥8 hours with ruptured membranes and receiving oxytocin OR 2. cervical dilation \>=6 cm and \<1 cm dilation change over ≥2 hours with ruptured membranes and receiving oxytocin Exclusion Criteria: Severe preeclampsia: as patients will be receiving magnesium and possibly labetalol for hypertension control Receiving other beta blocker Maternal heart rate \< 70 beats per minute, systolic blood pressure \<90 mmHg, or diastolic blood pressure \<50 mmHg on two sets of vital signs in the 1 hour prior to study drug administration: given that bradycardia and hypotension are possible side effects of propranolol History of any form of asthma: as this is a contraindication to beta blocker use Diabetes requiring insulin in labor: given the potential risk of neonatal hypoglycemia in the neonate Any cardiac condition for which β blockade is contraindicated (cardiogenic shock, sinus bradycardia, and greater than first degree heart block) Known hypersensitivity to propranolol Intrauterine fetal demise since different labor protocols are used in these women Major fetal congenital anomaly since rate of cesarean may be inherently different in these women, unrelated to labor