Association between Sexual Activity during Menstruation and Endometriosis: A Case-Control Study

The prevalence of endometriosis in the general population is estimated at 7-10%. Endometriosis is one of the causes of primary and secondary infertility in 30% of women. There are various risk factors for this disease. The present study aimed to determine the association between sexual activity during menstruation and endometriosis. This case-control study recruited 555 women visiting Alzahra Hospital in Tabriz, Northwest of Iran in 2017. The case group comprised 185 women of reproductive age with confirmed endometriosis. The control group comprised 370 women of reproductive age without endometriosis visiting the hospital for other problems. Data were collected using a researcher-made questionnaire based on previous studies. Univariate analysis was performed using the chi-squared test, and multivariate analysis was done using conditional logistic regression to control confounding variables. Based on multivariate logistic regression, the sexual activity of two groups during menstruation was significantly different. Having vaginal intercourse leading to orgasm during menstruation [OR (95% CI) = 5.23 (2.16 to 12.66)] and non-coital sexual activity leading to orgasm during menstruation [OR (95% CI) = 2.90 (1.28 to 6.55)] increase the risk of endometriosis approximately five and three times higher in those women who stated they had vaginal intercourse leading to orgasm during menstruation compared to those who stated they did not. Based on the results, vaginal intercourse or non-coital sexual activity leading to orgasm during menstruation increases the risk of endometriosis.