Use of oral contraceptives and risk of ulcerative colitis - A systematic review and meta-analysis.

Numerous studies have investigated the link between oral contraceptives and risk of ulcerative colitis (UC), but the results have been controversial. We systematically reviewed all relevant published studies and evaluated the association between the use of oral contraceptives and the development of UC by meta-analysis. Databases including PubMed, EMbase, CNKI and WanFang data were thoroughly searched from inception to September 2018 to collect the studies on the correlation between oral contraceptives and the risk of UC. The studies were screened according to the inclusion and exclusion criteria by two researchers independently, and the data were extracted and the quality was evaluated. Meta-analysis was performed using Stata 13.0 software. There were 12 studies involving 303,340 participants that reported on the association between oral contraceptives and UC. The pooled odds ratio (OR) of UC in oral contraceptive users was 1.25 [95% confidence interval (CI) 1.04-1.51, p =  0.02]. The risk was significant in the current oral contraceptive users (OR 1.49, 95% CI 1.12-1.96, p = 0.005) whereas the past oral contraceptive use was not significantly associated with UC (OR 1.17, 95% CI 0.95-1.43, p =  0.141). This study provides evidence of an association between the use of oral contraceptives and the onset risk of UC. The study also shows that the risk for patients who stop using the oral contraceptives was decreased. These findings may be used as important reference for the use of oral contraceptives and the management of UC patients.