DOuble-BAlloon Versus PROstaglandin E2 for Cervical Ripening in Low Risk Pregnancies

To compare the effectiveness and safety of double balloon catheter and vaginal insert Prostaglandin E2 in cervical ripening prior to Induction of Labor in low-risk women from 39+0 to 40+6 weeks of gestation.

Induction of labor (IOL) is a technique to establish vaginal delivery when the risks for continuing the pregnancy for mother or baby are higher than the risks of delivery. In case the cervix is unripe, cervical ripening before the onset of labor is needed. The two main mechanisms of cervical ripening can be categorized as mechanical or pharmacological.

A Cochrane systematic review and other recent meta-analysis have shown that cervical ripening with a balloon is probably as effective as induction of labor with vaginal Prostaglandin E2. However, this conclusion is based on low to moderate quality evidence. Only a limited number of randomized clinical trials (RCTs) have been conducted. Many of those suffering from small sample sizes and different study subjects, i.e. high-risk subjects only, and mixed population.

In current practice, induction of labor is not only used in high-risk patients with clear indications for pregnancy termination. The ARRIVE trial has shown a significant benefit of labor induction over expectant management among the low-risk population. Based on this evidence, the American College of Obstetricians and Gynecologists (ACOG) has suggested: "It's time to induce of labor at 39th week of gestation". Since then, there is a trend in favoring elective induction before the due date over expectant management. Besides, more and more pregnant women want to shorten the duration of pregnancy or to time the birth of the baby due to the convenience of the mother and/or healthcare workers.

This makes the optimal method of Induction of Labor in terms of effectiveness and safety for both mothers and their babies even more important. In this study, the investigators will compare the effectiveness and safety of double-balloon catheter and Prostaglandin E2 for elective labor induction in low-risk pregnancies.

Eligibility Criteria:
Inclusion Criteria:

1. Maternal age ≥ 18
2. Singleton pregnancy. Twin gestation reduced to singleton, either spontaneously or therapeutically, is not eligible unless the reduction occurred before 14 weeks gestational age.
3. Gestational age at randomization from at 39+0 to 40+6 weeks of gestation.
4. Cephalic presentation
5. Intact membrane
6. Unfavourable cervix (Bishop\<6)
7. Informed consent

Exclusion Criteria:

1. Maternal medical illness associated with increased risk of adverse pregnancy outcome (any diabetes mellitus, any hypertensive disorders, cardiac diseases, renal insufficiency, systemic lupus erythematosus, mental disorders, HIV positive, use of heparin or low-molecular weight heparin during the current pregnancy etc.)
2. Abnormal placenta: Active vaginal bleeding greater than bloody show or placenta previa, accreta or vasa previa
3. Abnormal amniotic fluid volume:

   * Oligohydramnios (MVP \< 2cm)
   * Polyhydramnios (MVP \> 10cm)
4. Abnormal fetus

   * Fetal demise or known major fetal anomalies
   * Fetal growth restriction (FGR) (EFW \< 3% or \< 10% and abnormal Doppler)
   * Non-reassuring fetal status (no fetal movements, abnormal fetal heart rate at auscultation)
5. Previous C-section
6. Planned for C-section or contra-indication to labour
7. Cerclage or use of pessary in current pregnancy
8. Refusal of blood product.
9. Participation in another interventional study that influences management of labour at delivery or perinatal morbidity or mortality