Familial aggregation of endometriosis in the Yale Series.

Objective: To investigate the familial aggregation and the risk of endometriosis among the female relatives of women with endometriosis. We also compared the epidemiologic characteristics of women with and without family history of endometriosis.

Patient(s): A total of 485 women with endometriosis and 197 infertile women without endometriosis underwent surgical investigation between August 1996 and February 2002.

Main Outcome Measure(s): The relative risk of endometriosis in a first-degree relative and the association between potential risk factors was estimated by chi2 and by crude adjusted odds ratios (95% CI).

Results: Endometriosis was identified in 9.5% of first-degree relatives of women with endometriosis versus only 1% of controls. The odds ratio for endometriosis in a first-degree relative was 10.21 (95% CI 2.45-42.5; P<0.001). In 3.9% of cases women with endometriosis reported that their mother had been diagnosed with endometriosis and 5.6% of cases that at least one sister had been diagnosed. Compared to the control group the odds ratio for the mother having endometriosis (7.99, 95% CI 1.06-60.1) or at least one sister having (11.55, 95% CI 1.56-85.59) were significantly elevated. Among women with endometriosis who reported a family history of endometriosis, and women with endometriosis who did not report a family history of endometriosis, there were no differences in demographic characteristics, body habitus, or menstrual parameters.

Conclusion(s): Women with endometriosis have a tenfold increased risk of endometriosis in their first-degree relatives.