title: Early life infections and onset of puberty: evidence from Hong Kong's children of 1997 birth cohort.
abstract: As economic development increases, puberty occurs at younger ages, and this could contribute to an increase in the incidence of cardiovascular diseases and hormone-related cancers. The factors that determine pubertal timing are poorly understood. The growth axis that is active during puberty is active in the first 6 months of life and interacts with the immune system. The authors examined whether prior infections, proxied by number of hospital admissions for infections at different ages, were associated with age at pubertal onset (Tanner stage II) using interval-censored regression in the Children of 1997 cohort, which is a population-representative Chinese birth cohort (n = 7,527). Mediation by growth was also examined. Girls, but not boys, who were hospitalized for infections at least twice in the first 6 months of life experienced pubertal onset about 8 months later (mean = 10.3 years, time ratio = 1.08, 95% confidence interval: 1.04, 1.12) than did those without such hospitalizations (mean = 9.6 years) after adjustment for infant characteristics and socioeconomic position (sex interaction: P = 0.02). There were no such associations for infections at 6 months to ≤8 years of age. Growth did not mediate the association. Early infectious morbidity in girls may be associated with later puberty, perhaps via suppression of the gonadotropic axis. The lowering of the number of infections in early life that accompanies economic development could be an additional factor that contributes to earlier puberty.
authors.affiliation: School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Man Ki
authors.initials: MK
authors.lastname: Kwok
authors.forename: Gabriel M
authors.initials: GM
authors.lastname: Leung
authors.forename: Tai Hing
authors.initials: TH
authors.lastname: Lam
authors.forename: C Mary
authors.initials: CM
authors.lastname: Schooling
mesh_terms: D000293:Adolescent; D041923:Adolescent Development; D000367:Age Factors; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006723:Hong Kong; D006760:Hospitalization; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007239:Infections / Q000150:complications* / Q000503:physiopathology; D008297:Male; D011627:Puberty; D012959:Socioeconomic Factors