Vaginal administration of the nitric oxide donor isosorbide mononitrate for cervical ripening at term: a randomized controlled study.

Objective: Our aim was to examine the effect of the nitric oxide donor isosorbide mononitrate on the uterine cervix at term and to evaluate possible adverse effects of this treatment.

Study Design: Term pregnant women were randomly selected to receive either 40 mg vaginally administered isosorbide mononitrate or placebo 4 hours before elective cesarean section. Cervical status, maternal blood pressure, maternal pulse rate, fetal heart rate, umbilical arterial Doppler indices, and various side effects were examined.

Results: Isosorbide mononitrate induced a significant increase in cervical distensibility. It also caused a significant change in maternal blood pressure and maternal pulse rate. In addition, the frequency of maternal headache and palpitations was significantly higher in the isosorbide mononitrate group versus the placebo group. However, the intensity of these symptoms was moderate.

Conclusion: Vaginal administration of 40 mg of isosorbide mononitrate induces cervical ripening at term. Although the majority of women experienced side effects, no serious clinical maternal or fetal adverse effects, resulting in specific medication or emergency cesarean section, were diagnosed.