Background Lung function, measured by FEV₁ and FVC, increases with age and height and it has an accelerated increase during adolescence.

Objective To describe the relation between sexual development and lung function at the age of 15 in a birth cohort.

Method All children (N=5249) born in the city of Pelotas, Brazil, were enrolled in a prospective birth cohort. In 2008, all cohort members were sought for a follow-up visit (response rate =85.7%). Sexual development was obtained using Tanner stages in five categories (from 1 to 5). VEF1 and FVC were measured in litres by spirometry and used as continuous variables. A multiple linear regression model stratified by sex and adjusted for family income, mother's height and wheezing, adolescent's height, age, smoking, and skin colour was performed. For girls it was also adjusted by age of menarche.

Results In boys, sexual development was not associated with FEV₁ or FVC. On the other hand, among girls the regression coefficients for FEV₁ and Tanner stages 2, 3, 4 and 5 were, respectively: β=0.07 (95% CI −0.04 to 0.18), β=0.13 (95% CI 0.02 to 0.24), β=0.15 (95% CI 0.04 to 0.26), β=0.14 (95% CI 0.02 to 0.27). The regression coefficients for FVC and Tanner stages 2, 3, 4 and 5 were, respectively: β=0.11 (95% CI −0.03 to 0.24); β=0.21 (95% CI 0.08 to 0.33); β=0.25 (95% CI 0.12 to 0.38) and β=0.23 (95% CI 0.09 to 0.38).

Conclusion Sexual development is associated with lung function among girls but not boys, probably due to the earliest sexual development in girls.