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Women's Health

Why Endometriosis Treatment Fails 1 in 3 Women—And What's Next

Author: Ailsa Cowell

April 03, 2026

Health Editor

By Ailsa Cowell

Health Editor

Ailsa Cowell is the Health Editor at mindbodygreen. She holds a M.S. in Human Nutrition from the University of Bridgeport and a B.S. in Environmental Studies and Sustainability from Northern Arizona University.

Image by Sergey Filimonov / Stocksy

April 03, 2026

Imagine you have debilitating, stabbing pains around your lower abdomen. You're in so much pain you're sweating, nauseous, and it's hard to think straight; you're exhausted and scared. And this happens every month.

Now imagine when you go in to see the doctor, you're given a treatment that you're told will take several months to work, but only two-thirds of women will actually experience any benefit at all.

This is just a snapshot of what it's like to live with endometriosis, which an estimated 10-15% of women of reproductive age are living with, though most women have to wait around 10 years to even get a proper diagnosis. Many women have full-body symptoms, but on the surface, they can look fine. They keep working, keep parenting, keep living. They don't have a verified, "approved" reason to take a break.

My personal experience with endometriosis

It turns out, I am one of those women. At age 38, I was finally diagnosed with endometriosis. After years of irregular cycles, extremely painful periods, and some pretty alarming misdiagnoses (like IBS and interstitial cystitis), I saw a new OBGYN who quickly ordered an ultrasound.

The results were clear: I had very large cysts on both of my ovaries, most likely endometriomas. While hormonal contraceptives were offered as an option, I knew I hadn't felt great on them in the past, and I also knew they may not actually help my symptoms. Because of their size, I was at risk of ovarian torsion, and I was living in fear of the pain that came and went each month.

I was lucky enough to have a surgeon at my OB's office who specialized in endometriosis excision, so I elected to have the surgery and was told afterwards that I did indeed have extremely extensive endometriosis. Most doctors are reluctant to diagnose the disease until they have actually biopsied tissue.

Since surgery, I've felt better than ever when it comes to my cycle, but there is always the risk that the endometriosis could grow back. Again, hormonal contraceptives are the typical recommendation, and new research has me curious about personalized testing that could better guide my decisions.

The problem with one-size-fits-all treatment

The first line of defense against endometriosis is often progestins—a class of hormones that suppress estrogen and reduce inflammation. For many women, they work for endometriosis pain (though that doesn't discount side effects like depression, which those with endometriosis are more susceptible to). But the frustrating reality is that about one-third of patients don't respond to progestin therapy at all.

Until now, there's been no way to know ahead of time who will benefit and who won't. So doctors prescribe, patients wait (often for months), and if symptoms persist, they start over with a new treatment. It's a pattern that plays out across many areas of medicine.

What new research reveals

A team of researchers at Yale set out to find a better way. Their goal: identify biological markers that could predict progestin resistance before treatment even begins.

What they discovered is promising. According to their study published in Biomarker Research1 a specific pattern of DNA methylation in circulating blood cells can predict whether a woman will respond to progestin therapy—with 95.2% accuracy.

DNA methylation is essentially a system of tiny chemical tags that sit on your genes and influence whether they're turned "on" or "off." Think of it like dimmer switches for your DNA. The researchers found that three specific genes—MMP20, NRXN1, and RNA5-8SN5—show distinct methylation patterns in women who are resistant to progestins, all with a simple blood test.

What this means for us

This research represents a shift toward personalized medicine—the idea that treatment should be tailored to our unique biology, not based on population averages.

Imagine walking into your doctor's office, getting a blood test, and knowing within days whether progestins are likely to work for you. If they're not, you and your doctor can skip straight to alternatives—whether that's a different medication, surgery, or other approaches—without losing months to a treatment that was never going to help.

This feels like a good place to point out, there are many schools of thought around improving endometriosis symptoms, such as reducing estrogen dominance through nutrition and lifestyle interventions. Progestin-based prescriptions are only one method, and accounting for your individual symptoms, needs, and health goals should all be factored into your