Younger menarche yet delayed breast maturity found for girls with higher total body fat
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Girls with higher total body fat are more likely to have menarche at a younger age and have slower breast development compared with those with normal total body fat, according to study data.
“Puberty looks different in girls with excess body fat — we found that they took longer to achieve fully mature breast tissue yet reached menarche earlier than girls with less body fat,” Natalie Shaw, MD, MMSc, a principal investigator at the National Institute of Environmental Health Sciences, told Healio. “They also had higher levels of follicle-stimulating hormone, inhibin B, and male-like reproductive hormones (eg, testosterone) that are made by the adrenal glands and the ovaries in the late stages of puberty.”
Shaw and colleagues enrolled 90 healthy, premenarchal girls (mean age, 10.9 years) with some breast development from the Raleigh, Durham and Chapel Hill region of North Carolina from 2016 to September 2020. All participants had no chronic medical conditions, were not taking any medications or supplements known to affect puberty and had no history of precocious puberty or premature pubarche. The girls completed one to eight study visits spaced 8 months apart. Visits included a physical exam with Tanner staging of the breast and pubic hair, a breast ultrasound for breast morphologic staging (where stages are A-E and A represents the pre-pubertal breast and E a fully mature breast), and blood and urine collection. A DXA scan, transabdominal pelvic ultrasounds and hand X-ray were performed during the first two visits. Menarche status was determined at each visit and every 3 months by phone through September 2020. Participants with an age-adjusted BMI falling in the fifth to 84th percentile were classified as normal weight (n = 54; mean age, 11.3 years), whereas those in the 85th percentile or higher were classified as overweight/obese (n = 36; mean age, 10.2 years).
The findings of the study were published in The Journal of Clinical Endocrinology & Metabolism.
At baseline, girls in the normal weight group had more advanced breast morphologic staging than those with overweight or obesity, which researchers attributed to the normal weight group’s older mean age. Analysis of breast morphological stage transitions showed mean total body fat did not affect the early stages of breast development. Girls with higher mean total body fat, however, moved more slowly out of breast stage D to stage D/E or stage E than those with lower mean total body fat. A 5% increase in mean total body fat was associated with a 26% slower transition out of stage D.
Analysis of reproductive hormones revealed an interaction between time and total body fat for follicle-stimulating hormones, inhibin B, estrone, total testosterone and androstenedione. Levels of those hormones were similar in all body fat groups at baseline but increased among girls with high total body fat after 1 year, decreased among those with low total body fat, and remained constant among participants with midrange total body fat. Total body fat had no effect on luteinizing hormone, estradiol and the modified vaginal maturation index, an index of urogenital epithelial cell estrogen exposure.
The median age at menarche was 12.4 years for the full cohort. Girls with higher total body fat at the first visit were more likely to have menarche at a younger age than those with lower total body fat, with the odds of reaching menarche at any given time point increasing by 3% with every 1 U increase in total body fat at the first visit (95% CI, 1-1.07; P = .05).
Shaw said the study was important because there had been no previous longitudinal studies analyzing how total body fat affects reproductive hormones or breast and ovary development, adding that more research is needed to examine the mechanisms behind the findings.
“The clinical consequences of the differences in reproductive hormones and breast development observed in pubertal girls with excess body fat and whether or not these differences persist after menarche are unknown, and these questions deserve further study,” Shaw said.
For more information:
Natalie Shaw, MD, MMSc, can be reached at natalie.shaw@nih.gov.
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