Recent Changes in Pubertal Timing in Healthy Danish Boys: Associations with Body Mass Index

摘要

Context: In the 1990s, the American population-based study NHANES III renewed the focus on possible secular trends in male puberty. However, no conclusions could be made on pubertal onset due to the lack of compatible data.Objective: The aim of the study was to evaluate secular trends in pubertal onset during the recent 15 yr and their relation to body mass index (BMI) in boys.Design and Setting: We conducted a cross-sectional study in 1991–1993 and a combined cross-sectional and longitudinal study in 2006–2008 (The Copenhagen Puberty Study) at a tertiary center for pediatric endocrinology.Participants: A total of 1528 boys aged 5.8 to 19.9 yr participated (n = 824 in 1991–1993, and n = 704 in 2006–2008). Genital and pubic hair stages as well as testicular volume by orchidometry were evaluated. Blood samples were analyzed for LH, FSH, testosterone, and SHBG.Main Outcome Measures: We measured age at onset of pubertal markers.Results: Onset of puberty, defined as age at attainment of testicular volume above 3 ml, occurred significantly earlier in 2006–2008 [11.66 yr (11.49–11.82); mean (95% confidence interval)] than in 1991–1993 [11.92 yr (11.76–12.08); P = 0.025]. Significantly higher LH, but not testosterone, levels were found in the 11- to 16-yr-old boys from 2006–2008 compared to 1991–1993 ( P = 0.020). BMI Z-score increased significantly from 1991–1993 [0.044 (?0.016 to 0.104)] to 2006–2008 [0.290 (0.219–0.361); P < 0.001]. Interestingly, pubertal onset and LH levels were no longer significantly different between study periods after adjustment for BMI.Conclusions: Estimated mean age at onset of puberty has declined significantly during the recent 15 yr. This decline was associated with the coincident increase in BMI.