Early breast development in overweight girls: does estrogen made by adipose tissue play a role?

BACKGROUND: Girls who are overweight/obese (OB) develop breast tissue but do not undergo menarche (the first menstrual period) significantly earlier than girls of normal weight (NW). It has been proposed that estrogen synthesized by adipose tissue may be contributory, yet OB do not have higher serum estrogen levels than NW matched on breast stage. We hypothesized that estrogen synthesized locally, in mammary fat, may contribute to breast development. This hypothesis would predict that breast development would be more advanced than other estrogen-sensitive tissues as a function of obesity and body fat. METHODS: Eighty premenarchal girls (26 OB, 54 NW), aged 8.2-14.7 years, underwent dual-energy x-ray absorptiometry to calculate percent body fat (%BF), Tanner staging of the breast, breast ultrasound for morphological staging, trans-abdominal pelvic ultrasound, hand x-ray (bone age, BA), a blood test for reproductive hormones, and urine collection to determine the vaginal maturation index (VMI), an index of estrogen exposure in urogenital epithelial cells. RESULTS: When controlling for breast morphological stage determined by ultrasound, %BF was not associated with serum estrogen or gonadotropin (LH and FSH) levels or with indices of systemic estrogen action (uterine volume, endometrial thickness, BA advancement, and VMI). Tanner breast stage did not correlate with breast morphological stage and led to misclassification of chest fatty tissue as breast tissue in some OB. CONCLUSIONS: These studies do not support the hypothesis that estrogen derived from total body fat or local (mammary) fat contributes to breast development in OB girls.

Longitudinal Investigation of Pubertal Milestones and Hormones as a Function of Body Fat in Girls.

CONTEXT: Epidemiologic studies have demonstrated that overweight/obese girls (OW/OB) undergo thelarche and menarche earlier than normal weight girls (NW). There have been no longitudinal studies to specifically investigate how body weight/fat affects both clinical and biochemical pubertal markers in girls. OBJECTIVE: To investigate the effect of total body fat on reproductive hormones and on the maturation of estrogen-sensitive tissues during puberty in girls. METHODS: Ninety girls (36 OW/OB, 54 NW), aged 8.2 to 14.7 years, completed 2.8 ±â€…1.7 study visits over 4 years. Visits included dual-energy x-ray absorptiometry to calculate total body fat (TBF), Tanner staging, breast ultrasound for morphological staging (BMORPH; A-E), pelvic ultrasound, hormone tests, and assessment of menarchal status. The effect of TBF on pubertal markers was determined using a mixed, multistate, or Cox proportional hazards model, controlling for baseline BMORPH. RESULTS: NW were older than OW/OB (11.3 vs 10.2 years, P < .01) at baseline and had more advanced BMORPH (P < .01). Luteinizing hormone, estradiol, and ovarian and uterine volumes increased with time with no effect of TBF. There was a time × TBF interaction for follicle-stimulating hormone, inhibin B, estrone, total and free testosterone, and androstenedione: Levels were initially similar, but after 1 year, levels increased in girls with higher TBF, plateaued in girls with midrange TBF, and decreased in girls with lower TBF. Girls with higher TBF progressed through BMORPH stage D more slowly but achieved menarche earlier than girls with lower TBF. CONCLUSION: In late puberty, girls with higher TBF demonstrate differences in standard hormonal and clinical markers of puberty. Investigation of the underlying causes and clinical consequences of these differences in girls with higher TBF deserves further study.