MONDAY, Aug. 9 (HealthDay News) -- The proportion of girls who experience breast development at ages 7 and 8 years is greater in girls today than in those born 10 to 30 years earlier, particularly among white females; and, maternal prenatal characteristics as well as weight and body mass index (BMI) gain during infancy influence various puberty outcomes, according to research published online Aug. 9 in Pediatrics.
Frank M. Biro, M.D., of the Cincinnati Children's Hospital Medical Center, and colleagues evaluated 1,239 girls, aged 6 to 8 years, from three geographically distinct centers. The researchers found that 10.4 percent of white, 23.4 percent of black non-Hispanic, and 14.9 percent of Hispanic girls had attained breast stage ≥2 at 7 years of age, with 18.3, 42.9, and 30.9 percent, respectively, attaining this state at 8 years of age. The researchers write that the proportion of girls who had breast development at ages 7 and 8 was greater than that reported in girls born 10 to 30 years earlier, and that this was particularly true for white girls.
Mildred Maisonet, Ph.D., of the U.S. Centers for Disease Control and Prevention in Atlanta, and colleagues obtained repeated self-assessments of pubertal development from approximately 4,000 girls aged 8 to 14 years. The researchers found that earlier puberty was associated with maternal initiation of menarche at younger than 12 years of age, smoking during pregnancy, and primiparity. In addition, weight and BMI gain during infancy were also associated with earlier puberty.
"Either such early factors have comparable influences on each of the hormonal processes involved in puberty, or processes are linked and awakening of one aspect triggers the others," Maisonet and colleagues conclude.
Abstract - Biro
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Abstract - Maisonet
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