A pregnancy is considered ''prolonged'' from 41 weeks of gestation. Prolonged Pregnancies (PP) are associated with increased maternal morbidity: emergency caesarean, 3rd and 4th degree perineal lesions and postpartum haemorrhage. Foetuses are at increased risk of oligohydramnios, meconium-staining and Fetal Heart Rate (FHR) anomalies. Around 15% of all pregnancies are prolonged.

A Cochrane review on induction of labour showed that a policy of labour induction at or beyond 41 weeks was associated with significantly fewer perinatal deaths. Thus the French College of Obstetricians and Gynaecologists stated, "induction of labour can be proposed to patients between 41+0 and 41+6 weeks of gestation". In cases where labour is induced and cervix is unfavourable, cervical ripening is advised. Methods of cervical ripening include pharmacological (prostaglandins) and mechanical (Foley catheter or trans-cervical double balloon) methods. Those two methods were compared in the PROBAAT trial among women with term pregnancies (beyond 37+0). The rates of caesarean section with these two strategies were identical, however uterine hyper stimulation with FHR anomalies occurred less when cervical ripening was mechanical.

Considering pharmacological cervical ripening is associated with more uterine hyper stimulation and more FHR anomalies, it may not be the most appropriate in cases of fragile foetuses that include cases of prolonged pregnancies. Considering prolonged pregnancies are associated with a risk of FHR anomalies and that cervical ripening with a pharmacological method is another factor which increases this risk: women with prolonged pregnancies could benefit from a more "gentle" cervical ripening.

At present, no particular method is recommended in cases of cervical ripening and prolonged pregnancies. We hypothesise that, in cases of prolonged pregnancies, mechanical cervical ripening, with less uterine hyperstimulation and fewer FHR anomalies, could be more appropriate and could reduce the rate of caesarean section for suspicion of fetal distress.

Inclusion Criteria:

• Pregnant women
• ≥ 18 years old
• With a singleton cephalic pregnancy between ≥41+0 weeks and ≤ 42+0 weeks of gestation
• Gestational age estimated from the first trimester ultrasound (realized between 11 and 13+6 weeks of gestation)
• With a decision of induction of labour
• Written informed consent obtained from subject
• Subject covered by or having the rights to the French Social Security system

Exclusion Criteria:

• Bishop score ≥ 6 (favourable cervix)

• Non cephalic presentation (breech, transverse)

• Severe preeclampsia defined as the presence of preeclampsia with at least one of the following items :

  • Severe maternal hypertension (systolic blood pressure ≥ 160 mm Hg and/or diastolic blood pressure ≥ 110 mm Hg)
  • Renal failure with oliguria (< 500 ml/24h) or creatinine > 135μmol/L, or proteinuria > 5 g/day
  • Pulmonary oedema, epigastric pain or HELLP syndrom (hemolysis, elevated liver enzyme, low platelets)
  • Eclampsia or neurologic persisting symptoms (visual disturbances, headache, increased reflexes)
  • Thrombopenia < 100 G/L

• Prior caesarean section or uterine scar

• Placenta praevia

• Suspected genital herpes infection

• Known VIH seropositivity (confirmed by blood serology)

• Premature rupture of membranes (PROM - continual leaking of amniotic fluid or positive test in favour of PROM)

• Foetus with suspected severe congenital abnormalities

• Pathological fetal heart rate

• Contra-indications to Propess®

• Contra-indications for using Cook® Cervical Ripening Balloon

• Women under guardianship or trusteeship