Investigating the impact of obesity on pubertal development in girls

National Institute Of Environmental Health Sciences

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Abstract

We launched the Body Weight & Puberty Study (BWPS; www.bodyweightandpuberty.niehs.nih.gov) the first pediatric-focused study ever to be conducted in the NIEHS Clinical Research Unit (CRU), in December 2015. We have enrolled nearly 100 subjects. We also launched the Girl's First Period Study in 2019 to study girls within 6 months of menarche. In the BWPS protocol, pre-menarchal girls between the ages of 8 and 14 undergo a physical exam (Tanner staging of breast and pubic hair; height, weight, and waist-hip ratio), breast ultrasound (morphological staging of glandular development), pelvic ultrasound (ovarian and uterine volumes, follicle counts, endometrial thickness), DEXA (% body fat), hand x-ray (bone age), and blood and urine tests (sex steroids, vaginal maturation index VMI of urogenital epithelial cells) Visit 1. Study procedures are repeated in 6 months Visit 2. Subjects continue to be followed every 6 months for blood and urine collection, physical exams, and breast ultrasound until menarche. In the Girl's First Period Study, reproductive hormone levels are measured daily in dried urine strips. These data are supplemented with biannual, intensive monitoring of a given menstrual cycle with weekly blood draws and pelvic ultrasounds. Findings: 1) obese girls staged as pubertal on physical exam (Tanner stage > 2) tend to have immature breast morphology on ultrasound relative to their normal weight counterparts, and 2) breast maturation scores correlate with other end-organ effects of estrogen (eg ovarian size, uterine size, bone age, and VMI) to the same degree in overweight/obese and normal weight girls, suggesting that thelarche in overweight/obese girls is driven by activation of the central components of the reproductive axis and hence ovarian estradiol, as opposed to peripheral sources of estradiol(eg adipose tissue). 3) in mid- to late-puberty, girls with higher percent body fat developed higher levels of androgens, FSH, and inhibin B. 4) in post-menarchal girls, preliminary data suggests there is a gradual increase in urinary pregnanediol over time that approaches adult hormone levels whereas there is no change in urinary LH or estrone conjugates.