Evening primrose oil for cervical ripening in term pregnancies: a systematic review and meta-analysis.

Induction of labor by using available, inexpensive and non-invasive methods with the least side effects is particularly important. A systematic review was conducted to assess the effect of evening primrose oil on cervical ripening in term pregnancies. In this systematic review and meta-analysis of clinical trials, a search was carried out in PubMed, Cochrane Library, Embase, Ovid, Scopus, Clinical Trials.gov, Google Scholar and Persian databases (Magiran, SID, and IRCT.ir) for published related articles without any time limit. The Cochrane handbook was used to determine the risk of bias of the included articles. The obtained data were analyzed in RevMan and reported in forest plots. The Odds Ratio (OR) was used to find the effect of the dichotomous data and the Mean Difference (MD) for the continuous data. The heterogeneity of the studies was assessed using I, T and Chi. The random effect was used instead of fixed effect if I >40%. A total of 28 titles and abstracts were extracted, 9 articles entered into the meta-analysis. The meta-analysis results showed significant differences between EPO and control groups in terms of bishop score (MD=1.32; 95% CI: 0.98 to 1.66), reducing caesarean section rate (OR= 0.61; 95% CI: 0.43 to 0.86), duration of first stage of labor (MD= -98.67; 95% CI: -140.98 to -56.38) and duration of second stage of labor (MD= -10.98; 95% CI: -21.86 to -0.09). There were no significant differences in terms of birth weight (MD= 100.97; 95% CI: -11.91 to 213.84) and the frequency of induction with oxytocin (OR= 0.53; 95% CI: 0.27 to 1.01). It seems evening primrose oil be effective for cervical ripening, reducing cesarean section rate and shortening the duration of labor. Due to the high heterogeneity of the studies, the researchers recommend further researches on the subject using a standard tool based on the CONSORT statement.