Effect of Castor Oil on Cervical Ripening and Labor Induction: a systematic review and meta-analysis

OBJECTIVES: Post-term pregnancy is a condition associated with increased maternal and fetal complications. Administration of castor oil causes cervical stimulation by increasing the production of prostaglandins. We examined the effects of castor oil on cervical ripening and labor induction through a systematic review and meta-analysis. METHODS: The search process was performed to obtain relevant articles from databases including Pubmed, Cochrane library, Scopus, Science direct, SID, Iran Medex, and Google Scholar using the English keywords of cervical ripening, post-term, castor oil, labor induction, Bishop score, and pregnancy considering all possible combinations without time constraints and their Persian equivalents from national databases. RESULTS: A total of eight related articles from the 19 primary studies were extracted and systematically reviewed. According to a cumulative chart, the difference in the post-intervention Bishop score was statistically significant (standard mean difference [SMD] 1.64, 95% confidence interval [CI] 1.67-2.11, p = 0.001), indicating an effect of castor oil on increasing the Bishop score. In addition, the difference in labor induction was statistically significant after the intervention (odds ratio 11.67, 95% CI 3.34-40.81, p = 0.001), indicating an effect of castor oil on increasing the odds ratio of labor induction (experience of vaginal delivery). CONCLUSION: This meta-analysis showed that oral administration of castor oil is effective for cervical ripening and labor induction. Midwives should closely monitor pregnant women with prolonged labor and collaborate with obstetricians to employ castor oil as a safe intervention to induce cervical ripening and labor to prevent undue caesarean surgery.