Intravaginal administration of isosorbide mononitrate for cervical ripening in prolonged pregnancy: a randomised clinical trial.

Prolonged pregnancies are associated with foetal and neonatal complications. This study was performed to evaluate the efficacy of intravaginal isosorbide mononitrate (IMN) for cervical ripening in prolonged pregnancies. 122 pregnant women were recruited. Women were assigned to 25 µg sublingual misoprostol plus 40 mg isosorbide mononitrate or placebo. Statistical analysis was done using SPSS software (version 23) and -test, Mann-Whitney and Chi-square test.  ≤ .05 was considered significant. The mean time between beginning of cervical ripening to Bishop score >6 was significantly shorter in IMN plus misoprostol group when compared to misoprostol plus placebo group ( = .02). The mean time from beginning of cervical ripening to the beginning of active phase of Labour was comparable between two groups ( = .274). The misoprostol plus IMN group had significantly shorter interval from the beginning of cervical ripening to the time of delivery. Isosorbide mononitrate in combination with misoprostol has a promising effect on cervical ripening and progress in labour.IMPACT STATEMENT Prolonged pregnancy is associated with foetal, neonatal, and maternal complications. Because of these complications, many obstetricians tend toward the induction of prolonged pregnancies to reduce perinatal morbidity and mortality. Isosorbide mononitrate is a nitric oxide donor agent which is used vaginally for cervical ripening in term pregnancies resulting in various outcomes. Isosorbide mononitrate in combination with misoprostol had a greater effect on cervical ripening and progress in labour than misoprostol alone in prolonged pregnancies. According to results of the current study; using isosorbide mononitrate in combination with misoprostol could enhance successful vaginal delivery in prolonged pregnancy. Evaluation of maternal satisfaction by using this protocol is recommended in future studies.