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

A new look at the theoretical causes of endometriosis: Narrative review

Endometriosis is a major health concern in women who have it. Unfortunately, there is no definitive cure except panhysterectomy with its sequelae including induction of premature menopause due to loss of ovaries. Therefore, revealing the causes of this puzzling disease is necessary to avoid contracting it, and to spare women the health disorders resulting from it and the difficulties of treating it. We aimed to study endometriosis with a focus on its theoretical causes. Its classification reports and theories of pathogenesis were identified and studied from available database searches. The causes of endometriosis remain mysterious. Many theories have been proposed to explain the etiology, but retrograde menstruation (RM) remains the closest in this regard. Although this theory is the most accepted in the pathogenesis of endometriosis, its causes are still a matter of debate, especially in women who do not suffer from obstructions to menstrual outflows, such as cases of congenital cervical stenosis and imperforate hymen. It is suggested in some studies that there may be a relationship between women who engage in sexual activity during menstruation and the development of endometriosis. It is concluded that endometriosis is a painful and debilitating disease. Identifying its causes is essential to control the disease and avoid any burdens on health. RM is the main theory for its pathogenesis but its causes are still uncertain. Sexual activity during menstruation may be a possible cause of RM but needs more evidence. Future studies are recommended to reveal all aspects of the pathogenesis of endometriosis.

The risk of endometriosis by early menarche is recently increased: a meta-analysis of literature published from 2000 to 2020

PURPOSE

The relationship between menarche age and endometriosis has been studied extensively; however, the results were inconsistent due to differences in study dates, populations, and methodology. The goal of this meta-analysis was to see how different research populations, dates, and types affected the estimated risk of endometriosis in early menarche.

METHODS

The terms "endometriosis", "early menarche", and other pertinent terms were searched in PubMed, Medline, and Embase. This meta-analysis comprised 16 papers published between 2000 and 2020, with a start year ranging from 1989 to 2017. Random effects were used to examine endometriosis risks in these articles. Study start years, countries, types (case-control and cohort studies), and quality (Newcastle-Ottawa scale, NOS) were all taken into account in further stratified analysis and meta-regression analyses.

RESULTS

Early menarche (< 12 years) was associated with a significant pooled risk of endometriosis with high heterogeneity (OR = 1.34, 95% CI 1.16-1.54, I² = 72.0%). Stratified analysis showed that this risk was increased in studies started after 2000 (OR = 1.62, 95% CI 0.96-1.35, I² = 74.4%), compared to those before 2000 (OR = 1.13, 95% CI 1.16-1.54, I² = 40.7%); additionally, this risk was higher in low-income countries (OR = 2.11, 95% CI 1.55-2.87, I² = 0%) than in other countries (OR = 1.25, 95% CI 1.09-1.43, I² = 70.6%). These results were further confirmed by meta-regression analysis (both P values < 0.1). No significant differences were found between different study types and NOS scores.

CONCLUSION

Our results suggested an increasing risk of endometriosis with early menarche, which was more noticeable in low-income countries. Large-scale studies are warranted.

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.

Ovarian hormones-autophagy-immunity axis in menstruation and endometriosis

Menstruation occurs in few species and involves a cyclic process of proliferation, breakdown and regeneration under the control of ovarian hormones. Knowledge of normal endometrial physiology, as it pertains to the regulation of menstruation, is essential to understand disorders of menstruation. Accumulating evidence indicates that autophagy in the endometrium, under the regulation of ovarian hormones, can result in the infiltration of immune cells, which plays an indispensable role in the endometrium shedding, tissue repair and prevention of infections during menstruation. In addition, abnormal autophagy levels, together with resulting dysregulated immune system function, are associated with the pathogenesis and progression of endometriosis. Considering its potential value of autophagy as a target for the treatment of menstrual-related and endometrium-related disorders, we review the activity and function of autophagy during menstrual cycles. The role of the estrogen/progesterone-autophagy-immunity axis in endometriosis are also discussed.