Why Do More Women Have Autoimmune Diseases?

The short answer

Many autoimmune conditions are more common in women, though the difference varies by disease. Researchers are studying how sex chromosomes, hormones, and other factors shape immune activity. That work may help explain why some conditions change during pregnancy, after childbirth, or around menopause.

Why women's immune systems differ

Many autoimmune diseases are more common in women. Sex chromosomes and hormones are two areas of research, alongside genetics, immune regulation, and environmental exposures. No two-factor explanation accounts for the entire disease category. Review of proposed mechanisms.

• Sex chromosomes. Many immune-related genes sit on the X chromosome. Some genes can remain active on both copies in people with two X chromosomes. Researchers are studying how this affects immune responses, alongside hormones and environmental factors. It is one possible contributor, not a complete explanation for an individual’s illness (review of mechanisms in autoimmunity).
• Sex hormones. Estrogen modulates immune activity, which is part of why autoimmune disease activity often changes across the menstrual cycle, pregnancy, and menopause.

The conditions this shows up in

The female skew is large across the board: roughly 9 in 10 for lupus and Hashimoto's thyroiditis. Multiple sclerosis (MS) shows a similarly striking, and worsening, pattern: population data tracking MS prevalence over time finds the disease now affects women more than twice as often as men, and that female-to-male ratio has been climbing for decades, suggesting something beyond genetics alone, likely a mix of genetic and environmental or hormonal factors, is widening the gap (Hittle et al., 2023, JAMA Neurol; DOI). MS matters especially here because it's an autoimmune disease of the brain and spinal cord, a direct bridge between the immune system and neurological health.

The hormonal-transition connection

Because estrogen influences immune activity, autoimmune conditions frequently change with hormonal life stages. Some flare or first appear around pregnancy or the postpartum period; others shift through perimenopause and menopause. Clinical guidelines for conditions like lupus specifically address how to manage contraception, pregnancy, and menopause, including when hormone therapy is appropriate (Andreoli et al., 2017, Ann Rheum Dis; DOI). If you have an autoimmune condition and you're entering perimenopause, that's a worthwhile conversation with your specialist.

The immune-brain thread

Some autoimmune conditions directly affect the nervous system; others can affect thinking through fatigue, pain, sleep, medication effects, or changes in an affected organ. Multiple sclerosis involves the brain and spinal cord. That does not make autoimmune disease in general a brain disease. Read about autoimmune brain fog.

When to see a clinician

Persistent unexplained fatigue, joint pain, hair or skin changes, or "off" spells that don't resolve deserve evaluation, autoimmune conditions are common and treatable, and early diagnosis helps. If you already have an autoimmune diagnosis, loop your specialist in around pregnancy and the menopause transition. This article is educational and not medical advice.

Frequently asked questions

Why are women more likely to get autoimmune disease?

Many autoimmune conditions disproportionately affect women, but a single percentage hides large differences between diseases and populations. Researchers study sex chromosomes, hormone signaling, and environmental factors together.

Which autoimmune diseases affect women most?

The skew is strongest for conditions like lupus and Hashimoto's thyroiditis (roughly 9 in 10). Multiple sclerosis affects women more than twice as often as men, and that gap has been widening over recent decades (Hittle et al., 2023).

Does menopause affect autoimmune disease?

It can. Because estrogen modulates immunity, autoimmune activity often shifts across hormonal transitions including menopause. The direction varies by condition, so discuss it with your specialist.

Is multiple sclerosis an autoimmune brain disease?

Yes. MS is an autoimmune condition affecting the brain and spinal cord, and it's markedly more common in women, a gap that's grown over time (Hittle et al., 2023), making it a clear link between immune and neurological health.

Can autoimmune disease cause brain fog?

Cognitive symptoms are common in several autoimmune conditions. See our dedicated explainer on autoimmune brain fog for the mechanisms and what helps.

Related reading

• Autoimmune brain fog: when your immune system clouds cognition
• Why are women more likely to get Alzheimer's?
• How your brain runs on estrogen

References

1. Andreoli, Bertsias, Agmon-Levin et al. (2017). EULAR recommendations for women's health and the management of family planning, assisted reproduction, pregnancy and menopause in patients with systemic lupus erythematosus and/or antiphospholipid syndrome. Annals of the Rheumatic Diseases.
2. Hittle, Culpepper, Langer-Gould et al. (2023). Population-Based Estimates for the Prevalence of Multiple Sclerosis in the United States by Race, Ethnicity, Age, Sex, and Geographic Region. JAMA Neurology.
3. Selmi, Gershwin (2019). Sex and autoimmunity: proposed mechanisms of disease onset and severity. Expert Review of Clinical Immunology.