Examining the evidence for recent secular changes in the timing of puberty in US children in light of increases in the prevalence of obesity.

This report reviews the available evidence from large population studies regarding a secular change in the timing and progress of puberty since 1960 in US children in light of concurrent increases in the prevalence of obesity. There probably was a secular decrease in the median age of onset and progression of genital development in Mexican-American boys and breast development Mexican-American girls in the 1980s and 1990s. The data are insufficient to do more than suggest corresponding trends in black boys and black girls, but there is no evidence of breast changes in white girls. Mean age of menarche decreased by approximately 3 months in US white girls and 5.5 months in US black girls between the late 1960s and approximately 1990. Evidence from a single study indicates the secular changes in age at menarche are consistent with the magnitude of secular change in obesity, although other evidence is equivocal.