Characteristics of pubertal development in a multi-ethnic population of nine-year-old girls

PURPOSE: Early age at menarche increases future disease risk. Secular decline in age at menarche has been attributed to body size characteristics, diet, and energy expenditure. Risk factors for puberty have been less frequently explored. METHODS: A cross-sectional study of 186 New York Metropolitan Area, 9-year-old girls (54 African-American, 70 Hispanic, 62 Caucasians) used interviewer-administered questionnaires to assess exposures. Height and weight were measured. Pediatricians assessed pubertal development according to Tanner stages. RESULTS: African-Americans were more likely than Caucasians to have achieved puberty as determined by breast or hair development (stage 2 or higher) [age-adjusted odds ratios and 95% confidence intervals = 4.91 (2.15-11.19) and 4.25 (1.85-9.77), respectively]. Pubertal development was similar among Hispanics and Caucasians. Adiposity and height were significantly positively associated with breast or hair development. More sedentary activity hours non-significantly increased the likelihood of hair development. Lower energy, but higher polyunsaturated fat, consumption were suggestive of an association with breast development. Vitamin C and hair development were inversely related. No other nutrients or physical activity measures were related to pubertal development. CONCLUSIONS: Results are consistent with height and adiposity being associated with pubertal development. Sedentary activity or diet might possibly influence maturation.