Sexual Activity during Menstruation as A Risk Factor for Endometriosis: A Systematic Review and Meta-Analysis.

Up to now, limited studies have been done to evaluate the effect of sexual activity during menstruation on the endometriosis. However, due to the menstrual-related symptoms of endometriosis, this study aimed to systematically review the published articles on the association between sexual activity through menstruation and endometriosis. This systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). This study examined all published observational studies on the association between sexual activity during menstruation and endometriosis, on the basis of the PICOS from conception until September 2021. The Newcastle-Ottawa Quality Assessment Scale was used to evaluate the quality of the articles. Also, Meta-analysis was conducted using Review Manager (RevMan 5.3). Out of the 1,905 retrieved articles of related databases, four studies comprised a total of 3641 patients (2251 cases and 1390 controls), which fulfilled the inclusion criteria, and equally encompassed high (2/4) and low (2/4) methodological quality, were reviewed. The results of all pooled studies showed that the probability of having sexual activity during menstruation is approximately two times higher in the women with endometriosis compared to women without endometriosis [odds ratio (OR)=1.80, 95% confidence interval (CI): 1.12 to 2.90, P=0.02, I2=78%, Tau=0.17, Chi2=13.72, P=0.003]. In this review, the sexual activity during menstruation was found to be an influencing factor for endometriosis. Due to the importance and complexity of endometriosis and the dearth of evidence on this topic, further studies with more robust designs are recommended.