Written by: Jaymee Salisi, News Writer

Endometriosis is a disease that causes endometrial tissue to grow outside of the uterus rather than inside. As a result, the body treats the displaced tissue growth like an infection, causing individuals with the disease to experience high pain sensitivity and inflammation in their abdominal area. According to research, up to 10% of cisgender women of childbearing age have this disease.

Based on research and independent studies — primarily done on cisgender women — on early development, hormone production, and reproductive-system physiology, researchers in the Crespi Laboratory found a connection between testosterone development and endometriosis.

According to the new theory, endometriosis is an early developmental disorder stemming from prenatal low testosterone development. The condition begins when the fetus is in the womb, and the effects are felt when the individual begins their first menstrual cycle.

“When your 12- or 16-week-old fetus is in the womb, there’s a sensitive period when the development of the reproductive system is taking place and the whole system is getting programmed,” evolutionary biologist Bernard Crespi told The Peak in an interview.

“Graduate student Natalie Dinsdale took the findings and realized this could be the key to understanding the disease as a whole,” Crespi said.

Though mainly diagnosed among people 25–35 years of age, endometriosis has also been found in cisgender girls as young as 11 years old. The theory can contribute to the treatment of pregnant people early in their first trimester and can aid new forms of treatment for those with the disease.

The main set of supporting evidence for the theory is the opposite levels of testosterone shown in endometriosis and polycystic ovarian syndrome (PCOS). According to Crespi, an excess in prenatal testosterone correlates with PCOS. In contrast, those with endometriosis may experience lower levels of testosterone development. These new findings may help identify endometriosis at an early stage. 

“There is good evidence from the literature that women who are relatively [ . . . ] low in weight tend to have higher rates of endometriosis. The reverse is true of PCOS,” Crespi said. 

He emphasized these are observed associations but not facts, as there are various factors that go into a person’s body size or shape. “It’s not something you can use in a predictive way.”

In terms of treatment for endometriosis, Crespi said there are “lots of little tweaks one can do to the endocrine system to bring it more in balance.” 

For instance, an individual can receive treatments to make their testosterone receptors more sensitive. This could support hormonal production by bringing it “closer to a typical range,” which can be 15–70 nanograms per deciliter of blood.

Crespi said pregnant people can try to avoid endocrine-disrupting chemicals which appear in bottled water and plastics to prevent hormone disruption for the fetus.

However, prevention is difficult because it is “hazardous to try to do anything pharmacologically with a first trimester fetus. They are very sensitive to disruption of any kind.”

More information on findings from Crespi’s research team can be found in their two research papers, The evolutionary biology of endometriosis and Endometriosis and polycystic ovary syndrome are diametric disorders.