Taller, Leaner Girls at Greater Risk of Developing Endometriosis, Study Says

Taller, Leaner Girls at Greater Risk of Developing Endometriosis, Study Says

Girls who are taller and leaner have a higher risk of developing endometriosis later in life, a 66-year follow-up Danish study suggests.

Identifying these risk factors during childhood may prove helpful for timely diagnosis and treatment of endometriosis, researchers say.

“A critical time window during which the disease develops is often missed, with women often experiencing diagnostic delays of several years,” Julie Aarestrup, PhD, researcher at the Center for Clinical Research and Prevention in Denmark, and the study’s first author, said in a press release.

“Our findings suggest that indicators of risk can be picked up at an earlier age, which might help speed up diagnosis so treatment can be started to slow the growth of endometrial tissue,” she said.

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

Although the symptoms of endometriosis may appear during early adolescence, diagnosis is usually delayed by a mean average of seven years. Recent data suggest that body size early in life may be used as a marker to assess the risk of endometriosis.

However, “no studies have evaluated height early in life in relation to endometriosis risks or associations between childhood body size and risks of adenomyosis,” the researchers wrote. Of note, adenomyosis is a condition thought to be associated with endometriosis, in which cells that usually line the inside of the uterus grow into its muscle wall instead.

In the study, researchers in Denmark investigated if birth weight, childhood body mass index (BMI) — a measure of body fat — and height could be associated with a higher risk of endometriosis and adenomyosis.

To that end, they analyzed data from 171,447 girls, ages 7 to 13, who were born in Denmark from 1930 to 1996, and registered in the Copenhagen School Health Records Register.

During follow-up, there were 2,149 cases of endometriosis and 1,410 cases of adenomyosis. In most cases, endometriosis affected the ovaries (44.2%), and was diagnosed when women reached a median age of 37 years. Adenomyosis was diagnosed even later, at a median age of 45 years.

“Our study covered practically all children attending school in the Copenhagen area over many decades, both before and after the obesity epidemic, with virtually all of them included in the follow-up analysis,” said Jennifer Baker, PhD, the study’s senior author. “This makes the results an important contribution to our limited understanding of endometriosis, while also highlighting how much more we need to learn about the biological processes behind it.”

Results showed that children who had a lower BMI had a significantly higher risk of developing endometriosis, including ovarian and pelvic peritoneal endometriosis. Also, childhood height was positively associated with endometriosis, with taller girls having a higher risk of developing the condition.

For example, if two seven-year-old girls had a body weight difference of 2.3 kg, the leaner girl had an 8% increased risk of having endometriosis later in life, while a 5.2 cm difference in height was associated with a 9% increased risk of the disease.

No similar associations were found for adenomyosis, and there was no link between birth weight and endometriosis or adenomyosis. The link between childhood BMI and height and the risk of endometriosis was similar across the entire 66-year period covered by the study.

The extensive follow-up of 66 years suggests that biological factors are the reasons for these links, rather than socioeconomic factors such as access to medications and living conditions.

The investigators also pointed out that estrogen — an important hormone for growing in height during puberty which also promotes the growth of endometrial cells — could be the link between increased height and endometriosis. However, the reasons why lower childhood BMI is linked to a higher endometriosis risk are still unknown.

Overall, “we found that leanness and tallness during school ages were associated with increased risks of endometriosis, but not adenomyosis,” the researchers wrote. “As the associations differed between endometriosis and adenomyosis diagnoses, our findings highlight that investigations of risk factors should be done separately for these diseases.”