According to the Endometriosis Foundation of America, endometriosis affects about 200 million women worldwide, yet its cause remains somewhat of a mystery. What makes one person develop the condition while another doesn’t? Researchers are still piecing together the full picture. Certain patterns and endometriosis risk factors have emerged to help answer questions like, "Who is at risk for endometriosis?" and "What are the main causes of endometriosis?" Genetic, lifestyle, and environmental factors may play a role.

Understanding the risk factors and causes can help determine if you’re more likely to develop endometriosis. Let’s explore the four potential causes and six risk factors for endometriosis, including the most recent theories and research.

Potential Causes

Endometriosis has several possible causes, including retrograde menstruation, changes in cells, surgery complications, and immune system problems.

1. Retrograde Menstruation

Retrograde menstruation is one of the most accepted theories for how endometriosis develops. Retrograde menstruation occurs when menstrual blood and small pieces of endometrium (tissue that lines the uterus) flow backward through the fallopian tubes and into the pelvic cavity, rather than out through the vagina. When this happens, endometrial cells can attach to organs outside the uterus, causing the tissue to grow in places where it shouldn’t.

Some research from the International Journal of Reproductive BioMedicine has reported that most women experience retrograde menstruation without developing endometriosis. However, this information might not be accurate, as diagnosing endometriosis is complex and requires a minimally invasive surgical procedure called laparoscopy. Because endometriosis can only be confirmed through surgery, diagnosis is often delayed.

2. Cell Changes

Cells can change from one form to a different form. This is called cellular metaplasia. Research shows this may be a potential cause of endometriosis because the cells outside of the uterus can change into cells similar to endometrial cells. It’s also theorized that hormones help to start this process.

Another theory is that endometrial cells might be accidentally transported to other parts of the body through your blood vessels or lymphatic system, a network of vessels and tissues that helps remove waste and transport immune cells.

3. Surgery Complications

Surgeries like cesarean sections or hysterectomies can sometimes cause endometrial cells to be moved accidentally to other areas of the body, potentially leading to endometriosis forming in scar tissue. This relocation may increase the risk of endometriosis developing in unusual places, which can cause complications and severe pain, especially if left undiagnosed for a long time.

4. Immune System Issues

A weakened immune system may struggle to clear away endometrial cells that end up outside the uterus, potentially allowing lesions and scar tissue to form and contribute to endometriosis.

Risk Factors

Development of endometriosis may involve hormone levels, genetics, ethnicity, environmental and lifestyle factors, body mass index (BMI), and age.

1. Hormone Levels

Estrogen plays a key role in causing endometrial tissue to grow outside the uterus. Elevated estrogen levels can stimulate the growth of endometrial tissue, including outside of the uterus. Hormone therapy or birth control that regulates or lowers estrogen is often prescribed to manage endometriosis.

People who are exposed to longer periods of estrogen are at a higher risk for endometriosis. You may have prolonged estrogen exposure if any of these statements are true:

• Your period started before age 11.
• You went through menopause later than usual.
• Your menstrual cycle is usually shorter than 27 days.
• You have heavy and long periods.

Uterine abnormalities, such as having a narrow cervix, can also increase the likelihood of developing endometriosis because it can block the regular flow of your period.

2. Family History

Research strongly suggests that endometriosis has a genetic component. If you have a close relative (such as a mother, sister, or daughter) with endometriosis, your risk of developing the condition is significantly higher. This familial connection suggests that endometriosis might be, at least in part, genetic. Ongoing studies are examining the role of specific genes and hereditary patterns to determine whether you're born with endometriosis or if it develops later.

3. Ethnicity

Research from the journal Reproduction and Fertility shows that endometriosis is more common in white women than in Black and Hispanic women. However, one review noted that it’s important to acknowledge the fact that racial bias may influence these findings, potentially leading to underreporting cases of endometriosis in other ethnic groups. Research is ongoing to better understand how ethnicity affects endometriosis risk factors and whether it leads to different outcomes across populations.

4. Environmental and Lifestyle Factors

Environmental factors and lifestyle choices are increasingly recognized as contributors to endometriosis risk. Exposure to chemicals like dioxins, commonly found in industrial waste, has been linked to a higher likelihood of developing endometriosis. In addition, some research shows that lifestyle habits such as alcohol intake, lack of physical activity, and a diet that is high in fat and red meat might raise the risk of endometriosis, but more research is needed. Regular exercise of more than four hours per week was associated with a reduced risk of developing endometriosis.

5. Body Mass Index

BMI is a measure that uses your height and weight to estimate if you’re in a healthy weight range. Studies on the link between BMI and endometriosis risk have shown mixed results. Some research suggests that having a lower BMI might be a risk factor, but this isn’t certain. This is different from many other health issues where a higher BMI is usually a risk factor. More research is needed to better understand any connection between BMI and endometriosis.

6. Age

Most people who have endometriosis are diagnosed between the ages of 20 and 40, although it can develop as early as your first menstrual period. You’re more at risk for endometriosis if your first period started before age 11.

Can Endometriosis Be Prevented?

Currently, there’s no definitive way to prevent endometriosis. However, here are some factors that are associated with a lower risk of developing endometriosis:

• If you give birth multiple times
• If your first period is after age 14
• If you lactate or breastfeed your baby for an extended time

Although pregnancy is linked to a lower risk of developing endometriosis, it’s not a treatment for the condition. You should discuss treatment options with your health care provider. The best way to manage endometriosis is to receive an early diagnosis, so it’s important to talk to your doctor if you’re experiencing symptoms of endometriosis.

Does Endometriosis Go Away on Its Own?

Endometriosis symptoms can go away on their own, usually after menopause, but symptoms can last from the time you get your first period until menopause. That’s when you experience a drop in your estrogen levels.

Until menopause, you may need constant treatment to manage your symptoms. Cleveland Clinic notes that some women find that pregnancy can temporarily ease endometriosis symptoms, but these symptoms often return after pregnancy when regular periods resume.

If you have any of the risk factors mentioned, or if you’re experiencing symptoms of endometriosis, it may be worth talking to your doctor about endometriosis.

Talk With Others Who Understand

On MyEndometriosisTeam, the social network for people with endometriosis and their loved ones, more than 136,000 members come together to ask questions, give advice, and share their stories with others who understand life with endometriosis.

What has your experience been like concerning risk factors of endometriosis? What is your advice to others seeking an endometriosis diagnosis? Share your thoughts and tips in the comments below or by posting on your Activities page.