Isonicotinic acid hydrazide (INH) versus extra-amniotic saline infusion (EASI) for cervical ripening at term: a randomised controlled trial.

The purpose of this trial was to compare extra-amniotic saline infusion (EASI) and intravaginal isoniazid (INH) for cervical ripening. This randomised clinical trial included 150 pregnant women who were undergoing induction of labour and who required pre-induction cervical ripening. Patients were randomly assigned to receive EASI or intravaginal INH. Bishop's score at the beginning of the study and before oxytocin infusion was not significantly different between INH and EASI groups. However, the time from first intervention to the beginning of the induction and also to the beginning of the active phase were significantly shorter in EASI group ( value ≤.001). Moreover, INH did not influence the labour process after the beginning of the active phase of labour. In conclusion, INH could be used for cervical ripening especially in the outpatient setting; however, it is a slower ripening agent compared to EASI.Impact Statement To date there has been only one study about the safety and effectiveness of isoniazid (INH) in cervical ripening at term pregnancy which has compared INH with misoprostol. The results of this study showed that vaginal INH is an effective agent for cervical ripening at term but in comparison to extra-amniotic saline infusion (EASI) it takes a longer time. INH can be used in outpatient settings for cervical ripening at term pregnancy which makes it convenient for patient and cost effective for both patient and health system. Further studies are needed to discover the clinical efficacy of INH in comparison to other ripening methods and also the best dosage of INH for cervical ripening.