Analyzing the association between menstrual coitus and endometriosis' pathogenesis: A narrative review

Across studies, the percentage of individuals reporting regularly engaging in menstrual coitus ranges between 4% and 43%. Although no clinical guideline recommends avoiding sexual activity during menstruation, according to some researchers such practice may favor both retrograde menstruation and sexually transmitted diseases, two phenomena that are thought to play a role in endometriosis' pathogenesis. Given this background, we analyzed the existing evidence regarding the association between menstrual coitus and the prevalence of endometriosis by conducting a PubMed database search on February 15, 2024. We considered all original, full-length studies written in English. Results were conflicting. When interviewing 489 infertile women, Filer and Wu found that the frequency of surgically diagnosed endometriosis was significantly higher among those engaging in menstrual coitus (17.5% versus 10.9%; p < 0.05). In their case-control study on 555 women with (n = 185) and without (n = 370) endometriosis, Mollazadeh and co-workers confirmed an increased risk of endometriosis among those engaging in menstrual coitus compared to those who did not (OR 5.23; 95% CI 2.16-12.66). However, in Meaddough and colleagues' retrospective case-control study on 2012 women, with (n = 1517) and without (n = 495) endometriosis, menstrual coitus was significantly less frequent in women with endometriosis compared to controls (27% versus 35%; p = 0.002). Treloar and co-workers also failed to prove such an association. The evidence available at the present moment is insufficient to confirm the hypothesis that menstrual coitus plays a role in the pathogenesis of endometriosis.