Indomethacin Versus Nifedipine for Preterm Labor Tocolysis

Patients presenting between 24-34 weeks gestation diagnosed with preterm labor who grant consent will be randomized by the pharmacy to receive oral nifedipine or oral indomethacin. Both the patient and primary medical provider will be blinded to the identity of the study drug. An abdominal ultrasound will be performed in the labor and delivery unit prior to the administration of the tocolytic in order to assess fetal position and fluid level, and to document fetal cardiac activity and movement, and will be repeated at 48 hours post-randomization. Following randomization, the patient will be given either 50 mg oral indomethacin with two pills of placebo, or 3 pills each containing 10 mg oral nifedipine for a total of 30 mg. The patients will then receive either 25 mg of oral indomethacin every 6 hours for 48 hours, or 20 mg of oral nifedipine every 6 hours for 48 hours. Tocolysis beyond 48 hours will not be used. Antibiotics and steroids for fetal lung maturity will be administered as per standard of care for preterm labor. Maternal side effects and delivery outcomes will be assessed from questionnaires administered by the study team following treatment, and/or from review of the patient's medical records.

Inclusion criteria

• Singleton and twin gestations
• Intact amniotic membranes
• No contra-indications to tocolysis
• 24-34 weeks gestation by last menstrual period and/or ultrasound
• Documented cervical change, and regular painful uterine contractions at least every 5 minutes, or at least 2 cm cervical dilation and 80% effacement

Exclusion criteria

• Ruptured amniotic membranes
• Signs/symptoms of chorioamnionitis (maternal temperature greater than 100.4 F/38.0 C, fetal tachycardia, uterine tenderness)
• Non-reassuring fetal heart rate tracings
• Contra-indications to indomethacin or nifedipine
• Contra-indications to tocolysis