Endometriosis occurs when endometrial-like tissue builds up outside of the uterus. That means the tissue can’t be expelled through the vagina during a period. Endometriosis may affect fertility in some people.
Once pregnant, symptoms of endometriosis may be temporarily alleviated. They tend to return once the pregnancy is complete.
It was previously thought that once a person with endometriosis became pregnant, the condition wouldn’t affect their pregnancy. However, some studies have shown a link between endometriosis and miscarriage, though the reason isn’t clear. A miscarriage is classified as a pregnancy loss that occurs before 20 weeks of gestation.
Here’s what science says about the link between endometriosis and miscarriage.
Current research on endometriosis and miscarriage
Two large studies looked at the relationship between endometriosis and miscarriage. Both studies found endometriosis to be a risk factor for miscarriage.
One review of studies found a significantly increased risk of previous miscarriage for people with endometriosis. The other cites that the increased risk of miscarriage for people with endometriosis is almost 80 percent, These studies were carried out in 2016 and 2017.
Another 2017 study found that milder cases of endometriosis in particular were related to a greater risk of miscarriage.
However, a 2019 cohort study of people undergoing in-vitro fertilization (IVF) found no statistically significant increased miscarriage risk in those with endometriosis.
More research is needed to definitively determine whether endometriosis is a risk factor for miscarriage.
Other Risk Factors
There are other factors that could increase the risk of miscarriage. Being 35 years of age or older is one risk that affects all genders.
For the pregnant partner, additional risks include:
- three or more previous miscarriages
- polycystic ovary syndrome (PCOS)
- particular viral or bacterial infections during pregnancy
- blood-clotting disorders
- abnormalities in the structure of the uterus
- exposure to certain medicines or chemicals during pregnancy
- smoking or using alcohol or cocaine during pregnancy
- excessive intake of caffeine during pregnancy
Many people wonder if they’ve done something wrong following a miscarriage. Most miscarriages occur because the fertilized egg in the uterus isn’t developing normally, not because of anything they did. Miscarriages aren’t caused by exercise, stress, or sex.