Gastric Emptying of Water and Sports Drink in Labor

This is a randomized un-blinded study comparing the gastric emptying halftime of water versus a carbohydrate-based sports drink. Cohorts Women in early labor who have not received pain medication will be enrolled in the study. This will be called the 'unmedicated' group. A second cohort of women who have received an epidural in early labor will be enrolled and studied using identical methods. This will be the 'epidural' group. Study Intervention Subjects in each group will drink one of two drinks: water or sports drink. The changing volume in the stomach will be measured using ultrasound over the next 60 minutes. Subjects will be asked their degree of hunger on a 10-centimeter visual analogue scale prior to drinking, and for the next two hours at regular intervals. Subjects will be free to consume as per obstetric protocols. The study will be finished once the patient consumes food or drink, feels hunger ≥4/10, or two hours after the sports drink. Hypothesis The primary hypothesis is that water will empty faster than the sports drink. A second hypothesis is that women with epidural pain relief will have similar gastric halftimes as women without pain medications.