Comparing the effects of vaginal and oral evening primrose oil on cervical ripening and labor progress among primiparous women

Evening primrose is a medicinal plant with potential effects on labor. This study aimed to compare the effects of vaginal and oral evening primrose oil on cervical ripening and labor progress among primiparous women.

This single-blind randomized clinical trial was conducted in 2020. Participants were 126 pregnant women with a gestational age of 39 weeks purposively selected from the obstetrics and gynecology ward of Valiasr hospital, Bafgh, Iran, and randomly allocated to vaginal evening primrose oil, oral evening primrose oil, and a control group. Participants in the vaginal evening primrose oil and the oral evening primrose oil groups received one 1000-mg evening primrose oil capsule per twelve hours for one whole week through the vaginal and the oral routes, respectively. The Bishop score and pregnancy outcomes were measured when participants referred to the study setting with labor pains.

After the intervention, the Bishop score in both intervention groups was significantly greater than the control group (P= 0.001). The length of the second stage of labor in the vaginal evening primrose oil group was significantly shorter than the control group (P= 0.009). There were no significant differences among the groups respecting the time interval between hospital admission and delivery (P= 0.21), 1 and 5-minute Apgar scores (P= 0.83), and (P= 0.37), need for induction (P= 0.26), and type of delivery (P= 0.26).

Vaginal and oral evening primrose oil administrations have significant positive effects on cervical ripening and the Bishop score and vaginal evening primrose oil have significant positive effects on the length of the second stage of labor.