The Effect of Outpatient Herbal Drugs on Cervical Ripening and Onset of Labor: A Systematic Review and Meta-Analysis

In recent years, outpatient cervical ripening and induction of labor has been considered because of reduced costs and increased patient satisfaction. Moreover, due to the side effects of chemical drugs, the tendency of patients for use of herbal medicines has increased. The aim of this study was to evaluate and summarize the results of clinical trials about outpatient herbal medicines in cervical ripening and onset of labor.

Clinical trials related to outpatient use of herbs in cervical ripening and onset of labor, were searched without time and language restrictions in Scopus, Pubmed, Cochrane library, Science direct, Scientific Information Database (SID), Magiran, and Google Scholar search engines until March 30, 2021. Data analysis was performed using STATA software.

16 articles that met the inclusion criteria were reviewed. Meta-analysis was only possible on castor oil and date fruit. The chance of spontaneous onset of labor in was 5.760 and 2.205 times the castor oil and date groups, respectively. Moreover, the increase in bishop score in castor oil group was 2 times higher than the control group. The results of funnel plot and Egger test found no evidence of publication bias (P = 0.710). Peganum, Sisymbrium, chamomile, and saffron were effective in cervical ripening and onset of labor. Evening primrose was effective on Bishop score, but had no effect on spontaneous onset of labor. Red raspberry leaves were not effective in spontaneous onset of labor.

Among the mentioned plants, castor oil and date fruit have more evidence in cervical ripening and onset of labor. Further studies with stronger methodologies are needed.