Effects of Misoprostol and Evening Primrose Extracts on Cervix Preparation for Labor Induction in Term Pregnancies

 Ripening is the process of preparing the cervix for induction of labor and is crucial to identify a low-complication, low-cost, and safe method of inducing labor before spontaneous labor begins. Therefore, this study aimed to demonstrate the impact of the evening primrose capsule on inducing labor, as well as to compare its effect to that of misoprostol.

 This prospective clinical trial study was performed on 200 low-risk pregnant women candidate for delivery in an academic hospital in Tehran from 2018 to 2020. Patients were randomly divided into two groups to receive 25 µg misoprostol vaginally or 500 mg evening primrose vaginal capsule to induce labor and repeated every three hours until reaching the bishop score > 4 in case of no effective up to three doses. The total drug dose, as well as maternal and neonatal outcomes evaluated and compared between groups.

 Although misoprostol was significantly more effective than evening primrose in increasing cervical bishop score in the inactive phase of labor, the active phase and delivery time were not different between the groups. Also, there was no significant difference between the two groups in the cesarean section rate. Maternal complications, including uterine hyperstimulation, headache, or gastrointestinal complications in the group receiving misoprostol were significantly higher in misoprostol group, but fetal complications, including Apgar score, pH, hospitalization, and meconium excretion, were not significantly different between the two groups.

 Evening primrose capsules are safe and can be used to induce labor because of the lower risk of hyperstimulation of the uterus and the higher tolerance. There should be more research done to see if this medicine can be used alone or in conjunction with misoprostol or mechanical dilators or if it can be administered at home rather than in the hospital.