The goal of induction of labor is to achieve vaginal delivery by stimulating uterine contractions before the spontaneous onset of labor. Generally, induction of labor has merit as a therapeutic option when the benefits of expeditious delivery outweigh the risks of continuing the pregnancy.

The first part of this process is called cervical ripening. The goal is to facilitate the process of cervical softening, thinning, and dilating with resultant reduction in the rate of failed induction and induction to delivery time. Cervical remodeling is a critical component of normal parturition.

Effective methods for cervical ripening include the use of mechanical and pharmacological methods.

There are many induction methods: pharmacological and mechanical.

Nowadays, induction of labour is one of the most frequent obstetric interventions, performed in 25% of pregnancies. Generally, better maternal and neonatal outcomes are achieved if the risks of continuing pregnancy outweigh the benefits.

Cervical ripening is the first part of the induction process, which consists in relaxing and softening the uterine cervix prior to the onset of uterine dynamics.

For this purpose, there are available pharmacological (mainly prostaglandin) and mechanical methods (including the balloon probes: Foley catheter or double cervical balloon). Despite being equally effective in vaginal delivery and caesarean section rate, there has been registered an increased risk of uterine hyperdynamic with the use of prostaglandin in contrast to the use of balloon probes, which may lead to an increased risk of fetal distress.

Concerning balloon probes, various published studies conclude that it is an effective and safe cervical ripening method, without increasing the risk of maternal infection (chorioamnionitis / endometritis) or neonatal infection.

The use of balloon probes could be established as first-choice method of induction of labour, reducing the risk of uterine hyperdynamic and the likelihood of intrauterine fetal distress derived from the use of prostaglandin.

The balloon probe safety makes it an ideal method for performing cervical ripening at home (out-patient) in low-risk pregnancies, increasing the satisfaction of women who desire it and reducing the economic cost for the hospital.

The purpose of this study is to assess the effectiveness and safety of double balloon catheter (CRB-Cook®) in induction of labour.

The main objective is to provide evidence that there are no differences in caesarean section rate between induction of labour performed with Cook double balloon catheter in out-patient and in-patient compared with a cohort of induction of labour with pharmacological methods (dinoprostone and misoprostol).

Two clinical studies will be carried out for this purpose:

1. Prospective cohort observational study
2. Historical case-control study

Inclusion Criteria:

• Pregnant women
• Age: ≧ 18 years
• Ability to read and understand informed consent
• Unique or multiple pregnancies (monochorionic or dichorionic twins)
• ≧37 weeks of pregnancy
• Unfavourable cervix (Bishop test: < 7)

Exclusion Criteria:

• >2 foetus pregnancies

• < 37 or ≧42 weeks of pregnancy

• Prelabour rupture of membranes

• Vaginal delivery contraindication

  • Placenta previa (occlusive and not occlusive)
  • Vasa previa
  • Transverse or oblique lie
  • Umbilical cord procubitus or prolapse
  • Corporal uterine surgery with entrance into the uterine cavity
  • Antecedent of ≧ 2 caesarean section
  • Antecedent of inverted T caesarean section
  • Antecedent of uterine rupture
  • Active genital herpes infection
  • Cervical carcinoma
  • Severe maternal pathology

• Breech lie

• ≥ 7 Bishop score

• Non-reassuring fetal cardiotocographic registration

• Indication of immediate delivery

• Stillbirth of malformed foetus

Also, patients to be included in the out-patient group should comply with the following criteria:

Inclusion criteria:

• Low-risk pregnancies
• ≤ 2 previous deliveries
• Patient acceptation and good comprehension of the instructions
• Maximum 30 minutes of distance to the hospital.
• Possibility of telephone communication at any moment
• To be accompanied by someone during the entire process at home

Exclusion criteria:

- Positive screening for vaginal / rectum group B streptococcal infection

Pregnant women