Red hair gene not linked to endometriosis

June 2006

Contrary to what has been suggested by some “cross-sectional” studies, red hair colour is not associated with a higher or lower risk of endometriosis, the results of a prospective study indicate.

However, the association may be affected by fertility status.

Previous reports have identified alterations in coagulation (clotting) and immune function among women with red hair. In addition, reports from cross-sectional studies have shown endometriosis to be more common among such women.

Dr Stacey Missmer, from Harvard Medical School in Boston, and colleagues investigated this association by analysing data from the Nurses’ Health Study II, an ongoing prospective study.

More than 90,000 women were included in the analysis and the main endpoint was confirmed endometriosis.

A total of 1,130 cases of endometriosis were identified during 379,422 person-years of follow-up, the report indicates.

Red hair colour was not tied to endometriosis in the overall analysis, which accounted for a variety of factors, such as parity (the number of times a woman has given birth) and body mass index. However, there was a suggestion that red hair colour slightly increased the risk of endometriosis among women who had never been infertile, but decreased the risk among those who were infertile.

“Further investigation into the potential linkage between red hair colour and coagulation or immune dysfunction may explain the observed difference in the association between hair colour and endometriosis with concurrent infertility vs. endometriosis without infertility,” the authors conclude.


Missmer SA, Spiegelman D, Hankinson SE, Malspeis S, Barbieri RL, Hunter DJ. Natural hair color and the incidence of endometriosis. Fertil Steril 2006;85(4):866-70.

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