Association between sexual maturation with neck circumference and body mass index in Brazilian schoolchildren

Abstract

Objective: We aimed to evaluate the association of neck circumference and body mass index with sexual maturation in nine-year-old children. Methods: This is a cross-sectional study nested in a Brazilian cohort study named the Predictors of Maternal and Infant Excess Body Weight Study. The present study used data from adult women and their children obtained at baseline and after 2 and 9 years of follow-up. The child’s sexual maturation was assessed according to Tanner stage. Logistic regression models adjusting for important covariates were used to examine the association of neck circumference with Tanner stages. Results: The prevalence in stages 2-5 for breast development in girls and for genitalia in boys was 69.1% and 51.3%, respectively. There was a higher (p<0.05) percentage of girls (35.3%) at stages 2-5 for pubic hair development when compared to boys (9.2%). For each unit increase in body mass index and neck circumference, the odds of girls being 2-5 stages for breast development were 1.52 (95% CI 1.17-1.97) and 2.67 (95% CI 1.40-5.09) times, respectively. In other words, the odds of girls being 2-5 stages for breast development were about 1.8 times higher when neck circumference was considered as a predictor, in relation to the body mass index measure (OR=2.67 vs. OR=1.52, respectively). Conclusion: Our results revealed that neck circumference, as well as body mass index, is associated with sexual maturation, especially in girls. This is an important result from a public health perspective because, in addition to body mass index, neck circumference may also be used for monitoring sexual maturation in children.