In a multicentre RCT 824 women with a term singleton pregnancy in cephalic presentation, intact membranes, an unfavourable cervix, an indication for induction of labour, and no prior caesarean section were randomly allocated to induction of labour with a Foley catheter (n=412) or vaginal prostaglandin E2 (PGE2) gel (n=412). Because of the nature of the intervention the study was not blinded. Caesarean section rates were similar in the two groups (23% vs 20%, RR 1.13, 95% CI 0.87 to1.47, n=819). Two serious maternal adverse events were recorded, both in the prostaglandin group: one uterine perforation and one uterine rupture. In a meta-analysis including the trial above the caesarean section rate showed no difference between Foley catheter group and PGE2 group (RR 1.02, 95% CI 0.80 to 1.30; 3 trials, n=1431). There was a trend favouring the Foley catheter compared with prostaglandin in uterine hyperstimulation (10 vs 23; RR 0.44, 95% CI 0.21 to 0.91; 3 trials, n=1431, p=0.03) and in post-partum haemorrhage (31 vs 50; RR 0.60, 95% CI 0.37 to 0.95; 3 trials, n=1042, p=0.03).
A Cochrane review included 23 trials involving a total of 3474 women. The overall number of women not delivered within 24 hours did not differ significantly between balloon catheter (Foley or Atad) compared with vaginal PGE2 (RR 1.26, 95% CI 0.94 to 1.68; 7 trials, n=1142). The risk of caesarean section was similar between groups (27% vs 25%) (RR 1.01, 95% CI 0.90 to 1.13; 21 studies, n=3202) for a lower risk of hyperstimulation (RR 0.19; 95% CI 0.08 to 0.43; 9 trials, n=1931). Oxytocin was used more often in the course of labour with balloon catheter (75% vs 50%) (RR 1.51; 95% CI 1.15 to 1.97; 6 studies, n=613 women, I² 82%). Eight studies compared balloon catheter and prostaglandins with administration of prostaglandins alone. The caesarean section rate was comparable between the groups (31% vs 33%) (RR 0.92; 95% CI 0.79 to 1.08; 8 studies, n=1295). The addition of balloon catheter to prostaglandins increased the likelihood of vaginal delivery within 24 hours (RR 0.45; 95% CI 0.28 to 0.71; 3 trials, n=698). Uterine hyperstimulation with fetal heart rate changes was seen less often in the combined group (12% vs 22%) (RR 0.53; 95% CI 0.35 to 0.78; 3 trials, n=509).