Can the outcome of induction of labour with oral misoprostol be predicted?

Abstract

OBJECTIVE : To determine predictors of outcome for induction of labour using oral misoprostol. SETTING : Labour ward at Kalafong Hospital in Atteridgeville, Pretoria, that serves an indigent South African urban population. METHODS : Data were collected prospectively on all women undergoing induction of labour with oral misoprostol from 1 March 2004 to 28 February 2005. Patients with contraindications to misoprostol induction were excluded. Univariate analysis and logistical regression analysis were performed to determine the significant predictors of success of induction of labour. Successful induction was defined as a vaginal delivery achieved within 24 hours. RESULTS : Five hundred and fifty-eight patients were included. There were three major indications for induction of labour, namely hypertension (45%), postdates (22.1%) and prelabour rupture of membranes (20.6%). Vaginal delivery was achieved within 24 hours in 52.4% of patients. The caesarean section rate was 42.1%. Fetal heart rate changes occurred in 25.6% and hyperstimulation in 1.4% of patients. Logistical regression analysis identified the following parameters as independent predictors of vaginal delivery achieved within 24 hours: primiparity (p < 0.001), Bishop score < 3 (p < 0.001), Bishop score 4 - 6 (p = 0.029), ruptured membranes (p < 0.001) and pre-eclampsia (p = 0.006). A method of scoring (Mbele score) has been developed making use of the results of this analysis in order to predict the successful outcome of induction.Conclusions. Primigravidity, intact membranes, pre-eclampsia and a low Bishop score were indicators of an unsuccessful outcome for induction of labour. It is thought that the Mbele score will be helpful in counselling patients on methods of delivery when they are admitted for induction of labour.