Prolonged labor, especially during the second stage of active expulsive effort (the pushing phase), is associated with increased risk of maternal complications (e.g. tissue trauma, postpartum hemorrhage, intra-amniotic infection). Developing an effective method to assist and maximize maternal expulsion effort should be of great value in reducing the number of complications, also including cesarean section or instrumental deliveries. Past studies published in the dental literature have shown that specially designed oral appliances that support the dental occlusion may increase the isometric strength of different muscle groups. Increased strength of the neck muscles could improve efficiency of the Valsalva maneuver in increasing intra-uterine pressure, and thus decreasing the duration of phase II of labor. Nulliparous women with uncomplicated singleton pregnancy will be randomly assigned to either the study group (Dental appliance) or the no dental appliance group. Duration of labor will be measured for both phase I and phase II. Rates for cesarean section and instrument deliveries and other complications will be charted as well as Apgar scores .
