In women with singleton gestations, to contemporarily assess the efficacy of oral nifedipine versus intravenous magnesium sulfate in the acute management of preterm labor in terms of defined early and late neonatal measures

Inclusion Criteria:

• Patients between 240/7-320/7 weeks gestation with findings consistent with preterm labor defined by at least one of the following criteria in accordance with regular uterine contractions (>4 uterine contractions in 20 minutes):

  1. Cervix > 2 cm in dilation or 80% effaced
  2. Positive fetal fibronectin (if performed).
  3. Demonstrated cervical change between two exams within 90 minutes.

Exclusion Criteria:

• Negative fetal fibronectin
• > 5cm dilatation
• Multiple gestations
• Known fetal anomalies or chromosomal abnormalities
• Ruptured membranes
• Significant vaginal bleeding
• Suspected chorioamnionitis
• Preeclampsia or uncontrolled hypertension
• Non-reassuring fetal heart tracing
• Placenta previa and/or accreta
• Placenta abruption
• Intrauterine growth restriction
• Maternal renal disease
• Underlying maternal cardiac condition
• Symptomatic hyperthyroidism
• Significant maternal disease
• Contraindication to nifedipine or magnesium
• Cerclage presence
• Tocolytic use within the last 12 hours
• Hypotension (defined as average blood pressure of <70/40's unresponsive to 1000 cc fluid bolus