Abstract
BackgroundA secular trend towards earlier puberty has been observed in girls, while a similar trend has been more uncertain in boys. We estimated current ages at pubertal development in both boys and girls.MethodsIn this population‐based cohort study, 14 759 of 22 439 invited boys and girls born from 2000 to 2003 in the Danish National Birth Cohort gave half‐yearly self‐reported information on puberty from the age of 11.5 years and throughout puberty. This late start of follow‐up limits the estimation of age at onset of puberty but not later pubertal milestones. We estimated mean age at attaining the following pubertal milestones in years with 95% confidence intervals (CI): age at menarche, voice break, first ejaculation of semen and Tanner stages for pubic hair development and breast development or genital development. Further, the difference in mean age at menarche between mothers and daughters was estimated.ResultsIn boys, voice break occurred at 13.1 (95% CI 13.0, 13.1) years, first ejaculation of semen occurred at 13.4 (95% CI 13.3, 13.4) years, and Tanner Genital Stage 5 occurred at 15.6 (95% CI 15.5, 15.6) years. In girls, age at menarche occurred at 13.0 (95% CI 13.0, 13.1) years and Tanner Breast Stage 5 occurred at 15.8 (95% CI 15.7, 15.9) years. Daughters had menarche 3.6 (95% CI 3.1, 4.2) months earlier than their mothers had.ConclusionThese data indicate that age at menarche has declined and to some extent support a decline in age at attaining other markers of pubertal development among boys.
Highlights
Existing data show that the age at menarche, a marker of pubertal development in girls, has declined over the last century in Europe and the US, but it remains unsettled whether the decline is continuing or has stopped.[1,2]
Population-based cohort study, we estimate the current age at attaining various pubertal milestones in Danish boys and girls, using half-yearly self-reported information on pubertal development
This study was based on the Puberty Cohort, nested within the Danish National Birth Cohort (DNBC)
Summary
Existing data show that the age at menarche, a marker of pubertal development in girls, has declined over the last century in Europe and the US, but it remains unsettled whether the decline is continuing or has stopped.[1,2] A decline in pubertal age in boys has been suggested, but this is still not investigated in detail.[2]. Childhood obesity, improved health, endocrine disrupting chemicals and prenatal exposures have been studied as potential causal factors.[3,4,5,6] Earlier timing of puberty is a potential concern[2] as it has been suggested as a risk indicator for some adult diseases, such as obesity, diabetes, heart diseases, breast cancer, and testicular cancer.[7,8,9,10] In this longitudinal, population-based cohort study, we estimate the current age at attaining various pubertal milestones in Danish boys and girls, using half-yearly self-reported information on pubertal development. We investigate whether daughters had earlier age at menarche than their mothers as an indicator of a potential decline in age at menarche in girls
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