The objective is to demonstrate the superiority of the strategy of labor induction by Cook® cervical ripening balloon between recommended strategy by dinoprostone (propess®) on the reduction of the time between cervical ripening and delivery in case of unfavorable cervix after 12 hours of PROM in term pregnant women.

The inclusion begins after 12 hours of PROM for a pregnant woman who has an unfavourable cervix and no B streptococcus. The case is discussed during the obstetric staff every morning.

If the cervix is unfavourable (cervical Bishop's score <6), the information of the study is given to the patient and the consent collected.

An antibiotic is started at the beginning of the inclusion by amoxicillin (or clindamycin in case of allergy of amoxicillin) to prevent choroamnionitis.

After randomization, the patient is included in one of the two groups: Cook ® balloon or Propess ®.

• In the Cook cervical ripening balloon group: the device is introduced by a resident or a doctor. No traction on the probe was done. It is left in place for maximum 12 hours. Oxytocin is added at the end of the first 6 hours even if device is fallen. An epidural analgesia can be started before or after the installation of oxytocin
• In dinoprostone vaginal group: the device is placed in vaginal fornix by the midwife for maximum 24 hours. If Propess ® is fallen before the first 12 hours, another one could be introduce if the cervix stayed unfavourable.

After 24 hours, it is removed. If they are any contraction, oxytocin is started with or without epidural analgesic.

• The fetal heart rate is monitoring 30 minutes before and after the insertion of the device. After, the patient has a monitoring each 6 hours.
• Since the oxytocin is started, the monitoring is registered in continue until the delivery.

Inclusion Criteria:

• Pregnant women

  • 18 years old With a singleton live cephalic pregnancy ≥ 37+0 weeks Gestational age estimated from the first trimester ultrasound (realized between 11 and 13+6 weeks of gestation) PROM without spontaneous labour in the 12 hours after the rupture. The diagnostic of PROM is clinic or biologic (ActimProm® test).

Unfavourable cervix (Bishop's score < 6) Agreement of the patient after clear, loyal and appropriate information Subject covered by or having the rights to the French Social Security system

Exclusion Criteria:

• Vaginal infection by B streptococcus or in urinary sample during actual or anterior pregnancy Meconium fluid amniotic Contraindication of vaginal delivery (placenta praevia, …) Temperature > 38,2°C Suspicion of chorio-amnionitis among Newton requirements Intra-uterine growth restriction < 3rd percentile with Doppler abnormalities History of cesarean and uterine scare Suspected genital herpes infection Known VIH seropositivity (confirmed by blood serology) Fetus with suspected severe congenital abnormalities Pathological fetal heart rate (see appendix 1) Contra-indications to Propess®, Cook® Cervical Ripening Balloon, Oxytocin Women under guardianship or trusteeship

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