Lean and tall girls are at increased risk for endometriosis, but not adenomyosis, in adulthood, according to study results published in Annals of Human Biology.

Body size, including body mass index (BMI) and height, have been linked to the risk for endometriosis and adenomyosis in adulthood. However, given that endometriosis and adenomyosis may present early in adolescence, studies of risk factors in adulthood may miss a critical age window for the development of disease. Using a Danish population-based cohort, the study researchers aimed to investigate the relationship between body size in childhood and the risk for endometriosis and adenomyosis diagnosis.

For 171,447 women, childhood and early adolescent (aged 7-13 years) weight and height were obtained from the Copenhagen School Health Records Register. Women were followed into adulthood and outcomes were obtained from national health registers. Over the course of follow-up (5 million person-years), 2149 women were diagnosed with endometriosis and 1410 with adenomyosis.

Childhood BMI at age 7 years was inversely associated with the risk for endometriosis (hazard ratio [HR], 0.92 per BMI z score; 95% CI, 0.88-0.96). This association was observed regardless of endometriosis location, with a similar inverse relationship observed in ovarian (HR, 0.91 per BMI z score; 95% CI, 0.85-0.98) and pelvic peritoneal endometriosis (HR, 0.87 per BMI z score; 95% CI, 0.78-0.97). In contrast, childhood height at age 7 years was positively associated with the risk for endometriosis (HR, 1.09 per height z score; 95% CI, 1.05-1.14). Similar risks were observed for both locations of endometriosis. Associations with BMI, height, and endometriosis risk were similar at all childhood ages.

Although the risk for adenomyosis tended to be higher in women with high childhood BMI values (HR, 1.04 per BMI z score; 95% CI, 0.98-1.10), these risks reached significance at only some ages, and there was no clear association found between childhood BMI or height and risk for adenomyosis.

Birth weight was available for 130,569 women in the study, of whom 1780 were diagnosed with endometriosis and 1097 with adenomyosis. Birth weight was not associated with the risk for endometriosis or adenomyosis in adulthood.

The researchers noted that the study follow-up period spanned multiple decades, over which the awareness and diagnosis of endometriosis and adenomyosis has changed. However, no birth cohort effects were observed with regard to the identified associations, suggesting that this did not significantly confound the study results.

“[W]e found that leanness and tallness during school ages were associated with increased risks of endometriosis, but not adenomyosis,” the study authors investigators concluded. “[T]hese findings provide novel insights into the [etiology] of endometriosis and adenomyosis and aid in the current limited understanding of the critical time window for anthropometric exposures in relation to risks of these diseases.”

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The clinical features of endometriosis and adenomyosis are similar, and some professionals have suggested that they may exist together on a continuum of diseases. However, the researchers noted that, “our findings highlight that investigations of risk factors should be done separately for these diseases.”

Reference

Aarestrup J, Jensen BW, Ulrich LG, Hartwell D, Trabert B, Baker JL. Birth weight, childhood body mass index and height and risks of endometriosis and adenomyosis [published online March 9, 2020]. Ann Hum Biol. doi:10.1080/03014460.2020.1727011

This article originally appeared on Endocrinology Advisor