A phase I, open-label trial to determine a safe dose of oral misoprostol required to augment labor in nulliparous women diagnosed with arrest of dilation.

Inclusion Criteria:

• nulliparous
• gestational age of at least 36 weeks
• singleton gestation
• cephalic presentation
• reassuring fetal heart rate
• 4 cm or greater cervical dilation
• ruptured membranes with clear amnionic fluid
• intrauterine pressure catheter in place
• less than 200 MVU's

Exclusion Criteria:

• non-reassuring fetal heart rate
• meconium-stained amnionic fluid
• previous uterine incision
• maternal fever
• pregnancy-induced hypertension or other pregnancy-related complications
• known fetal anomalies
• placenta previa or unexplained vaginal bleeding
• estimated fetal weight of 4,500 grams or greater
• evidence of cephalopelvic disproportion
• any moderate or severe preexisting disease
• contraindication to the use of prostaglandins