The Balloon Project for Birth Induction

The study was a multicenter randomized study conducted at 7 labour yards in Denmark (Glostrup, Hillerød, Svendborg, Rigshospitalet, Næstved, Frederiksberg and Hvidovre). Participants were included from December 11 2002 till September 29 2005 after approval from The Danish National Committee on Biomedical Research Ethics and the data legislation. All participants were included after written and oral informed consent.

Eligible for inclusion were pregnancies with intact fetal membranes, vertex position and unripe cervix (Bishop score < 6) who had usual indications for induction of labour, i.e. prolonged pregnancy, pre-eclampsia/ hyper-tension, placental insufficiency, diabetes mellitus and twins.

Women were excluded under the following circumstances: Spontaneous labour or rupture of membranes, placenta previa, acute fetal distress, specific infections vagina/cervix (GBS, condyloma, acute herpes), asthma, glaucoma and allergy to latex. The participants were randomised to treatment arm by 'telephonic automatic voice response system randomisation'.

Induction of labour methods The balloon group The Double Balloon Catheter was applied (Atad 5) with 80 ml NaCl installed intrauterine above the intern orificium and 80 ml below in cervix/vagina. The Balloon catheter was inserted in the evening (8-9 p.m.) if the Bishop-score was below 6, however if the score was above 6 or the insertion was impossible the participant was considered failure. The catheter was removed after 12 h (or before if needed). The labour induction was continued by amniotomy either directly or after 2 hours mobilisation and laxative or after additional 2 hours of intravenous syntocinon drip. If by then amniotomy was not possible the participant was considered failure. After amniotomy if necessary for progression of contractions intravenous oxytocin-drip was started for 2-3 hours (figure 1). If further induction was necessary the participant was considered failure.

The minprostin group The prostaglandin 2 minprostin (3mg) was applied vaginally in the morning the day of induction if Bishop score was 6 or below. After 4-5 hours a second minprostin was inserted if amniotomy was not possible. If the labour was not induced the first day the procedure it was repeated the following day. If labour was not established within 48 hours after the first minprostin the participant was considered failure.

Inclusion criteria

• pregnancies with intact fetal membranes
• vertex position
• unripe cervix Bishop score < 6)
• usual indications for induction of labour, i.e. prolonged pregnancy, pre-eclampsia/ hyper-tension, placental insufficiency, diabetes mellitus and twins

Exclusion criteria

• Spontaneous labour or rupture of membranes
• placenta previa
• acute fetal distress
• specific infections vagina/cervix (GBS, condyloma, acute herpes)
• asthma
• glaucoma
• allergy to latex