Prostaglandin induced cervical ripening under tocolytic cover in primiparae: results of a double blind placebo controlled trial

Abstract

In a double blind trial, 60 nulliparae with a modified Bishop score of less than or equal to 5 requiring induction of labour, received either 8 mg of salbutamol or an identical placebo orally, 30 min before vaginal administration of 2 mg prostaglandin E2 gel. Women in the salbutamol group experienced less uterine activity over the subsequent 12 h compared with those given placebo, and fewer (35%) commenced labour compared with the placebo group (62%). However, the change in cervical score was significantly less in the salbutamol group (mean 3.0, SD 3.1) than that in the placebo group (mean 5.8, SD 3.2), and the prostaglandin treatment to delivery time in the salbutamol group (mean 26.1 h, SD 6.49) was significantly longer than that in the placebo group (mean 19.3 h, SD 7.95). The first stage of labour lasted greater than 10 h in 11 women in the salbutamol group compared with five in the placebo group. Side effects attributable to salbutamol occurred in 10% of the treated women but in none of their fetuses and fetal outcome was satisfactory and similar in both groups. Our findings show that salbutamol can suppress prostaglandin-induced uterine activity during cervical ripening, which could be an advantage in induction of labour where a planned delivery is preferred. However, the poorer outcome of labour in salbutamol-treated women mitigates against this approach.