Abstract and Introduction
Abstract
Earlier puberty has been associated with numerous adverse mental, emotional, and physical health outcomes. Obesity is a known risk factor for earlier puberty in girls, but research with boys has yielded inconsistent findings. We examined sex- and race/ethnicity-specific associations between childhood obesity and puberty in a multiethnic cohort of 129,824 adolescents born at a Kaiser Permanente Northern California medical facility between 2003 and 2011. We used Weibull regression models to explore associations between childhood obesity and breast development onset (thelarche) in girls, testicular enlargement onset (gonadarche) in boys, and pubic hair development onset (pubarche) in both sexes, adjusting for important confounders. Clear dose-response relationships were observed. Boys with severe obesity had the greatest risk for earlier gonadarche (hazard ratio = 1.23, 95% confidence limit: 1.15, 1.32) and pubarche (hazard ratio = 1.44, 95% confidence limit: 1.34, 1.55), while underweight boys had delayed puberty compared with peers with normal body mass index. A similar dose-response relationship was observed in girls. There were significant interactions between childhood body mass index and race/ethnicity. Childhood obesity is associated with earlier puberty in both boys and girls, and the magnitude of the associations may vary by race/ethnicity. Prevention of childhood obesity may delay pubertal timing and mitigate health risks associated with both conditions.
Introduction
Earlier puberty is associated with numerous adverse outcomes throughout the life course. Girls who develop earlier are at higher risk for anxiety, depression, body dissatisfaction, and early sexual initiation during adolescence,[1–5] as well as cardiac problems, all-cause mortality, and breast and reproductive cancers later in life.[2,6–9] Growing evidence also suggests that early-maturing boys experience negative consequences such as behavioral misconduct, substance use,[1,5] and psychological problems during adolescence,[10,11] as well as higher risks of testicular and prostate cancer later in life.[2,12]
Childhood obesity is a known risk factor of earlier pubertal development in girls. However, few studies have explored the associations between childhood obesity and pubertal timing among boys, with inconsistent results. Most studies of boys have been conducted outside the United States, where the rate of childhood obesity is substantially lower.[13–20] Additionally, US studies have been limited by predominantly White cohorts and/or have failed to include large racial/ethnic minority populations such as Asians and Pacific Islanders[21–23] despite evidence of racial/ethnic differences in pubertal timing.[24,25] Further, most studies include varying or later measures of obesity and therefore cannot establish temporality between exposure and outcome.[14–17,19–23] This is especially important given that adolescents experience natural increases in weight at puberty (fat mass in girls and fat-free mass in boys).[26] We conducted a longitudinal study using a large and diverse cohort of boys and girls from Northern California to examine sex- and race/ethnicity-specific associations between childhood (ages 5–6 years) body mass index (BMI) and timing of pubertal onset, using clinician-assessed sexual maturity ratings (SMRs).
Am J Epidemiol. 2022;191(12):2026-2036. © 2022 Oxford University Press
