Preterm birth is a major public health problem, and actual treatments are not very efficient. The purpose of this study is to test the efficiency of a combined use of Montelukast and Nifedipine to treat preterm labor. Investigators aim to reduce uterine contractions more efficiently than with the use of Nifedipine only.

An inflammatory process is involved in 60% of preterm births. Moreover, investigators previously demonstrated that enzymes of lipoxygenase pathway are present in uterine smooth muscle, and that an additive tocolytic effect can be obtained from the combined use of Montelukast and Nifedipine.

Methods:

This is a double-blinded randomized controlled assay performed at the CHUS on two groups of 50 women. Women will be selected when admitted for preterm labor with a gestational age between 26 and 34 weeks.

The first group will receive Nifedipine for 48 hours, as described by the standard protocol at the CHUS, in addition to 10 mg of Montelukast per day, until delivery or 35 weeks of pregnancy.

The second group will receive Nifedipine for 48 hours, as described by the standard protocol at the CHUS, in addition to a placebo per day, until delivery or 35 weeks of pregnancy.

Cervical secretions and urine will be sample at the admission, after one week and every two weeks during treatment.

Inclusion Criteria:

• women with 24-34 weeks of pregnancy
• indication for tocolysis

Exclusion Criteria:

• preterm labor before 26 or after 34 weeks of pregnancy
• minor patients
• patients with other obstetrical pathology
• twin pregnancies
• fetal distress
• severe congenital fetal malformation
• anti-phospholipid syndrome
• lupus
• gestational diabetes
• nephropathy
• congenital heart disease
• obvious causes of infection associated with prematurity
• patients with viral infections (HIV, hepatitis)
• patients already treated with Montelukast