Abstract
The literature on the relationship between adiposity and the onset of puberty is extensive, both in size and in the length of time this question has been alive in the biomedical literature. It is easy to wonder, then, whether there is anything new to be learned in this crowded field. In this issue of the Journal, Deardorff et al. (Am J Epidemiol. 2022;191(1):7-16) show that it is still possible to innovate in this area. The authors report on the relationship between body mass index at age 5 years and a variety of markers of the onset of puberty. Consistent with the current literature, they show no association between body mass index at age 5 and pubertal onset in boys. They also show an association between obesity at age 5 with earlier onset of secondary sexual characteristics in girls, making an important subject-matter contribution that addresses many of the concerns of the existing literature in assigning causality. At the same time, the authors make an important, although less evident contribution to the practice of epidemiology for studies where the assessment of pubertal status is of interest.