Biomarkers of Uterine Muscle Physiology

Inclusion Criteria: * Maternal age: 18-41 years at the due date * Term gestation: 37-41 weeks estimated gestational age (EGA) * Single fetus in a vertex presentation: Pregnancy with only one fetus that is in a head down position with the occiput leading into the pelvis upon admission to the hospital. Exclusion Criteria: * Pre-existing or gestational diabetes requiring medical management: The diagnosis of diabetes of any kind requiring management with medications including but not limited to insulin, glyburide, and metformin as indicated in the health record. * Pre-existing or gestational hypertension or pre-eclampsia requiring medical management: The diagnosis of hypertension of any kind requiring management with medications including but not limited to long-term hypertension management such as methyldopa and short-term or emergency hypertension management such as labetalol or magnesium sulfate as indicated in the health record. * Suspected fetal anomaly or intrauterine growth restriction: Any diagnosed fetal anomalies or intrauterine growth restriction as indicated in the health record. * Use of amnioinfusion prior to sample collection: Amnioinfusion, the infusion of fluids into the uterus using an intrauterine catheter may affect AFL concentrations. Any amnioinfusion prior to sample collection will exclude participants from continued participation. * Fetal distress prior to or during sample collection: Category 3 fetal heart tracing as defined by the National Institute o…