What causes endometriosis?

Medical professionals are still not sure exactly what causes endometriosis. The most likely causes are thought to include: 

• genetics: if your mother, sister or aunt, for example, has endometriosis, your risk of developing endometriosis increases
• retrograde (reverse) menstruation: blood shed during your period flows through the fallopian tubes into the pelvic cavity instead of leaving your body.

Some of the other possible causes include: 

• endometrial cells travelling through your blood or lymphatic system to other areas of your body¹
• an immune system issue that prevents your body from being able to destroy endometrial tissue found outside of the uterus
• environmental factors such as weight, diet, and alcohol consumption
• endometrial cells attaching themselves to a surgical incision after surgery
• hormones that can change unformed cells into endometrial-like cell implants during puberty.²

Endometriosis is most likely the result of a combination of factors, which makes it harder to prevent. 

¹ Mayo Clinic, Endometriosis, Mayo Clinic website, n.d., accessed 10 June 2021. https://www.mayoclinic.org/diseases-conditions/endometriosis/symptoms-causes/syc-20354656

² Mayo Clinic, Endometriosis.