Patient with a risk of preterm labor (ultrasound cervical length < 25 mm +/- described or recorded uterine contractions) before 32 weeks of gestation will be hospitalized to receive tocolytic drugs and antenatal corticosteroid therapy according to the investigators gold standard protocol. After 48 hours, the participants will be assessed by examination, external tocodynamometry and the measure of cervical length by ultrasound. Stabilized patients will be included and randomized into 2 groups of 210 patients each. The first group A will benefit from the standard protocol (extended hospitalization of 2 or 4 days according to the clinical and ultrasound assessment); whereas the second group, B, will have the benefit of the detection of phIGFBP-1.If the result proves negative, patients could be discharged early at day 2. In the case of a positive result, patients will follow the standard procedure because of the low positive predictive value of the test. The main outcome is the total duration of hospitalization.
It consists of evaluating the advantage of routine detection of phIGFBP-1 to reduce the total duration of hospitalization for patients with a risk of preterm labor before 32 weeks of gestation without increasing the number of preterm labour.