BMI, Height Associated with Endometriosis Risk in Women

Julie Aarestrup, PhD

Women who were tall and lean were more often diagnosed with endometriosis, new study findings showed.

The findings suggested that endometriosis risk indicators could be apparent at early ages, which could speed up diagnosis and treatment of the condition.

Julie Aarestrup, PhD, and colleagues obtained the health records to examine whether birth weight, childhood body mass index (BMI), and height were associated with risks of endometriosis and adenomyosis. Although lean and tall girls were more likely to be diagnosed with endometriosis, the same did not apply for adenomyosis.

Aarestrup, from the Center for Clinical Research and Prevention at Bispebjerg and Frederiksberg Hospital in Denmark, and the investigative team used the Copenhagen School Health Records Register, which contained information from school health examinations on nearly all of the children born from 1930-1996. The Danish National Patient Register contained information on endometriosis and adenomyosis diagnoses.

The team included women who were born during the 66-year study period, had an identification number, and were alive and living in Denmark at the age of >15 years old.

Overall, 171,447 women were analyzed and 130,569 made up a sub-sample cohort.

Among those in the study, 2149 women had an endometriosis diagnosis and 1410 were diagnosed with adenomyosis over 40 years and 5 million women-years of follow-up. The median age at diagnosis was 37 years old for endometriosis overall and 45 years old for adenomyosis.

Childhood BMI was inversely and significantly associated with endometriosis risks. Girls with the highest BMI had a moderately reduced risk of endometriosis.

Aarestrup and the team also found that childhood BMI was inversely related to risks of ovarian (HR, .91; 95% CI, .85-.98) and pelvic peritoneal (HR, .87; 95% CI, .78-.97) endometriosis. There was very little evidence on the association between childhood BMI and adenomyosis risks, though HRs were mostly positive (HR, 1.04; 95% CI, .98-1.1).

Unlike childhood BMI, height was positively associated with endometriosis risks, with the tallest girls having the highest risks (HR, 1.09 at 7 years old; 95% CI, 1.05-1.14) per z-score. There was not strong evidence of associations between height and risks of adenomyosis (HR, .97; 95% CI, .92-1.02) per z-score at 7 years old.

Among girls with below-average height z-scores, the shortest girls had the lowest risks.

A 1 z-score difference in BMI between 2 7-year-old girls was associated with an 8%, 9%, and 13% increased risk of overall endometriosis and ovarian and pelvic peritoneal endometriosis for the leanest girl.

Leanness and tallness during school age were both associated with increased risks of endometriosis, but not adenomyosis, the investigators concluded. The findings highlighted that studies and future investigations of risk factors should be done separately for such diseases.

What’s more, the results provided insights into the cause of endometriosis and adenomyosis and could lead to a better understanding of the time window for anthropometric exposures due to risks of the conditions.

The study, “Birth weight, childhood body mass index and height and risks of endometriosis and adenomyosis,” was published online in the journal Annals of Human Biology.