Labour induction at term: clinical, biophysical and molecular predictive factors

The aim of this multicentric study is to compare clinical, biophysical and molecular parameters in the prediction of the success of labour induction with prostaglandins.

We included 115 women, who underwent to labour induction at term with vaginal prostaglandin gel. We evaluated the diagnostic efficiency of endocervical phosphorylated insulin-like growth factor-binding protein (phIGFBP-1), cervicovaginal interleukins 6 (IL-6) and 8 (IL-8). We analyzed the transvaginal sonographic measurement of cervical length. A receiver-operating characteristics (ROC) curve was used to determine the most useful cut-off point. A multivariate logistic regression model was used to analyze the combination of significant predictive variables following univariate analysis. We analyzed all the data searching for the parameters that best predict the beginning of the active phase of labour within 12 h.

36.5 % of the patients delivered within 12 h. The Bishop score was >4 in the 43 % of patients with an active phase. The best cut-off values at ROC curves for cervical length, IL-6 and IL-8 were respectively 22 mm, 5 mg/dl and 20,237 mg/dl. At univariate analysis, all predictors of success, with the exception of IL-6, were significantly associated with the beginning of the active phase. Multivariate analysis of the Bishop score (OR 2.3), phIGFBP-1 test (OR 11.2) and IL-8 (OR 6.6) showed that the variables were independent and therefore useful in combination to predict the success of labour induction.

The phIGFBP-1 test is a fast and easy test that can be used with Bishop score and IL-8 to reach an high positive predictive value in the prediction of the success of labour induction with prostaglandins.