Obesity and secondary sexual maturity in boys

Background Obesity induces earlier secondary sexual maturity in girls. However, results of studies in boys have been inconclusive.Objective To assess for an association between obesity and sexual maturity in boys.Methods This was a prospective cohort study on 133 obese and 133 matched-for-age, non-obese, prepubertal boys, aged 9 to 10 years. They were observed every 4 months for a two year period. Obesity was defined as the BMI ≥the 95th percentile, according to the Centers for Disease Control 2000 growth charts. Secondary sexual maturity was defined as testicular volume of ≥4 mL and Tanner staging of pubic hair of ≥P2. Two trained nurses and a pediatric resident collected the data.Results By the end of the study period, 106 (79.7%) obese boys had attained a testicular volume of 4 mL or more, vs. 85 (63.9%) non-obese boys (RR 1.78; 95%CI 1.19 to 2.67; P=0.004). Furthermore, 81 (60.9%) obese boys attained pubic hair states of Tanner stage P2 vs. 37 (27.8%) non-obese boys (RR 1.85 95%CI 1.46 to 2.34; P