Greater body fat, tobacco smoke exposure predict early puberty in girls

Girls with higher body fat percentage and whose parents smoke are likely to undergo precocious puberty, as reported in a study.

Researchers followed 195 girls aged 6–8 years for 2 years to examine child-related and parental variables in relation to earlier thelarche. A physician evaluated breast development by inspection and palpation.

Fifty-seven girls (29.0 percent) achieved thelarche during a 2-year follow-up. In multivariable logistic regression models, the incidence of early thelarche was predicted by body fat percentage (each single unit increase: odds ratio [OR], 1.11, 95 percent confidence interval [CI] 1.06–1.17; p<0.001), parental smoking (OR, 2.64, 95 percent CI, 1.21–5.77; p=0.015), and height (1-cm increase: 1.21, 95 percent CI, 1.11–1.32; p<0.001).

Thelarche timing also showed associations with lower parental education (OR, 3.65, 95 percent CI, 1.21–11.02; p=0.022) and higher maternal pre-pregnancy body mass index (each single unit increase: OR, 1.11, 95 percent CI, 1.03–1.20; p=0.009). These associations were largely explained by body fat percentage.

There was no association seen for gestational age, birth weight, physical activity, sedentary time, diet quality, or parental alcohol consumption.

The onset of puberty, especially in girls, requires enough energy stores in adipose tissue, the researchers explained. As such, the increasing prevalence of overweight children may have contributed to the secular trend of earlier sexual maturation in girls.

However, the researchers acknowledged that some of the girls in the study might also have had isolated thelarche.