Association of Obesity with Onset of Puberty and Sex Hormones in Chinese Girls: A 4-Year Longitudinal Study.

OBJECTIVE: To examine the influence of childhood obesity on the early onset of puberty and sex hormones in girls. METHODS: Healthy girls with different percentages of body fat at baseline (40 obese, 40 normal, and 40 lean) were recruited from three elementary schools in Shenyang, China. These girls (mean age 8.5 years) were also matched by height, school grade, Tanner stage, and family economic status at baseline. Anthropometry, puberty characteristics, and sex hormone concentrations were measured at baseline and at each follow-up visit. The generalized estimating equation model and analysis of variance for repeated measures using a generalized linear model were used to determine the differences in puberty characteristics and sex hormones among three groups. RESULTS: Over 4 years, mean age of breast II onset was earlier among obese girls (8.8 years) than normal girls (9.2 years) and lean girls (9.3 years). The prevalence (%) of early-maturation in the obese, normal, and lean groups was 25.9%, 11.1%, and 7.4%, respectively. Obesity was associated with an increased risk for breast stage II (year 2: RR, 6.3; 95% CI, 1.9-21.1 and year 3: RR, 6.9; 95% CI, 0.8-60.1). None of the girls experienced menarche in the first year; however, by the fourth year 50.0% of obese girls had menarche onset, which was higher than normal weight (27.5%) and lean girls (8.1%). The mean estradiol level increased with age in the obese, normal, and lean groups. The mean estradiol concentration was higher in obese girls than in normal and lean girls throughout the 4-year period (P<0.05). CONCLUSIONS: Childhood obesity contributes to early onset of puberty and elevated levels of estradiol in girls.

Sexual development in prepubertal obese boys: a 4-year longitudinal study.

The objective of the study was to evaluate whether or not sexual development differs between boys with prepubertal obesity and boys of normal weight. We enrolled healthy obese and normoweight schoolboys from Shenyang City, Liaoning, China. Eligible boys were at Tanner stage 1 and 8 years of age at baseline. We measured testosterone and estradiol concentrations in the saliva and assessed auxology annually for 4 years. In all 56 obese and 56 normoweight boys, the height, weight, body composition, and sex organ volume increased with age. The percentages of body fat, fat mass, and lean mass were all higher in obese than in normoweight boys. The mean testicular volume was smaller in obese boys than in normoweight boys. The sex hormone concentrations increased with age, except for testosterone in obese boys in year 3 of follow-up. In year 4, estradiol concentrations were significantly higher in obese boys than in normoweight boys. Excessive adiposity in prepubertal boys might affect testicular volume, possibly because of high estradiol and low testosterone concentrations.