Endometriosis has long been recognised as more than just a “reproductive disorder.” It’s a systemic, inflammatory condition that affects around 1 in 10 women of reproductive age. Beyond the debilitating pain and fertility struggles it can bring; new research is painting a clearer picture of its ties to autoimmune disease — and the findings are eye-opening.
A recent large-scale study published in NPJ Women’s Health set out to answer a big question: are women with endometriosis more likely to develop autoimmune conditions, and if so, how soon after their diagnosis?
The Study at a Glance
- Data analysed: Over 332,000 women with endometriosis and 1.2 million matched controls, using U.S. insurance databases.
- Timeframe: Diagnoses tracked within two years of an endometriosis diagnosis.
- Autoimmune conditions studied: 10 in total, including rheumatoid arthritis, Hashimoto’s thyroiditis, systemic lupus erythematosus (SLE), multiple sclerosis (MS), pernicious anaemia, Sjögren’s syndrome, myositis, vitiligo, Graves’ disease, and type 1 diabetes.
The results? Women with endometriosis were about twice as likely as women without endometriosis to be diagnosed with at least one autoimmune condition within that two-year window.
Which Conditions Showed the Strongest Links?
Not all autoimmune diseases were equally represented. The standout associations were with:
- Sjögren’s syndrome (immune system attacking mucus producing glands) – odds up to nearly six times higher.
- Myositis (immune system attacking muscles) – risk up to seven times higher.
- Rheumatoid arthritis (where immune system attacks lining of joints), lupus (where immune system attacks of tissues and organs), Hashimoto’s (where immune system attacks thyroid causing it to slow down), multiple sclerosis (where the immune system attacks the myelin sheath around nerves), and pernicious anaemia (where the immune system attacks the intrinsic factor needed for B12 absorption) – all showed consistent, moderate increases in risk.
- Graves’ disease (where the immune system attacks the thyroid causing it to speed up) and vitiligo (where the immune system attacks the melanocytes of the skin) – more mixed results, sometimes not statistically significant once corrections were applied.
- Type 1 diabetes (where the immune system attacks the pancreas)– association faded when looked at over a longer three-year period.
In short, the overlap is real, but it isn’t equal across the board.
Why the Link?
The study didn’t prove causation, but it did highlight shared biology that makes this connection plausible:
- Chronic inflammation: Endometriosis lesions release cytokines, prostaglandins, and inflammatory mediators. The same culprits show up in autoimmune diseases like lupus and rheumatoid arthritis.
- Immune dysfunction: Women with endometriosis often have more neutrophils and macrophages, fewer natural killer cells, and altered T-cell function — a profile that mirrors autoimmune dysregulation.
- Genetics: Some studies suggest shared genetic variants, particularly with rheumatoid arthritis and MS, although findings here are mixed.
- Systemic impact: Endometriosis isn’t confined to the pelvis — it’s increasingly recognised as a whole-body inflammatory condition.
What This Means Clinically
This study reinforces something many women already know from lived experience: endometriosis rarely exists in isolation. The higher rates of autoimmune diagnoses suggest that clinicians should keep a broader lens when assessing women with endometriosis — especially in the early years after diagnosis.
It also highlights the diagnostic challenges. Both endometriosis and autoimmune diseases often take years to be properly identified. Because of this, some of the “two-year overlap” may be due to the fact that once doctors start investigating, they uncover multiple co-existing conditions.
Interestingly, research has also suggested that women with both endometriosis and autoimmunity may be more likely to have advanced disease. In other words, autoimmunity could be a red flag for more severe endometriosis.
Strengths and Limitations
This was one of the largest studies ever to examine endometriosis and autoimmunity together, using two very different insurance datasets (private and Medicaid). The consistency of findings across both adds weight to the results.
But, like all research, it had limitations:
- Claims data can miss mild or undiagnosed cases.
- We still don’t know whether endometriosis triggers autoimmunity, or whether shared inflammation sets the stage for both.
- Key details like BMI, lifestyle, and endometriosis stage weren’t available in the databases.
So while the associations are robust, the “why” is still a work in progress.
The Bigger Picture
What does this mean for women living with endometriosis?
- Awareness is power: Knowing there’s a higher risk of autoimmunity means symptoms like fatigue, unexplained joint pain, or neurological changes should never be brushed off.
- Holistic care is essential: Addressing inflammation, supporting immune balance, and looking beyond the reproductive system is crucial.
- Research is evolving: Studies like this are helping reframe endometriosis as not just a gynaecological disorder but a systemic inflammatory disease.
From a Naturopathic perspective – gut health is king.
Many of the proinflammatory pathways in endo start with specific opportunistic gut bacteria and lower levels of commensal bacteria. It is well agreed that the gut is the centre and beginning of the immune system so should always be the place to start
The takeaway.
This isn’t in your head: endometriosis rarely travels alone. Research shows women with endo are significantly more likely to develop autoimmune conditions in the early years after diagnosis. Think joint pain, thyroid issues, neurological changes — these deserve attention. The study reinforces the need for holistic, multi-system care for endometriosis
Study link; https://pubmed.ncbi.nlm.nih.gov/40547362/