Indometacin is a cyclooxygenase agent from the NSAID family that has been used to treat preterm contractions since the 70's by preventing the synthesis of prostaglandins. It has been shown to be significantly more effective than placebo and postpone labor for 7-10 days, prolong pregnancies above 37 weeks of gestation and reduce numbers of small for gestational age neonates.

Nifedipine is a calcium channel blocker agent that has been shown to reduce rates of labor within 48 hours from treatment.

Previous studies comparing rectal Indometacin to oral nifedipine were inconclusive.

Prostaglandins are synthesized in the uterus and the uterine cervix and therefore local administration of Indometacin may be more effective than other forms of administration, as been shown in a previous study.

In this study we aim to compare vaginal Indometacin administration to a commonly used tocolytic agent, nifedipine.

Inclusion Criteria:

• Singe fetus
• Gestational age between 24+0/7 and 31+6/7
• At least one uterine contraction in ten minutes for at least 20 minutes upon tocography admission
• Cervical parameters: 1 cm dilation or more or 80% cervical effacement or cervical length 20mm or less

Exclusion Criteria:

• Rupture of membranes
• Vaginal bleeding
• Cervical dilation ≥5cm
• Known fetal malformations
• Fetal heart rate abnormalities
• Suspected placental abruption of adherent placental syndrome
• Known sensitivity to one of the drugs used in the study (Indometacin and nifedipine)
• Maternal hypotension and known aortic or mitral stenosis
• Presence of cervical cerclage
• Previous administration of tocolytic drugs in current pregnancy

Pregnant women

Caregivers will receive a closed envelope with the drug to be used. since the routes of administration are different, from that point on the caregiver and patient will be aware of chosen drug