EFEITO DO PESO AO NASCER E DO ESTADO NUTRICIONAL INFANTIL NA MENARCA PRECOCE EM ADOLESCENTES DA COORTE BRISA

Abstract

Introduction: In recent decades, a secular trend toward earlier age at menarche has been observed, which is associated with negative health outcomes. Although its determinants are not yet fully understood, genetic, socioeconomic, environmental, and nutritional factors have been identified as important influences, along with prenatal and birth conditions such as birth weight, prematurity, and maternal age at menarche. It is believed that birth weight, especially when low, may affect growth patterns and body composition in childhood, predisposing individuals to excessive adiposity and early menarche. Objective: To analyze the effect of birth weight on the occurrence of early menarche, mediated by nutritional status at 13–34 months of age, among adolescents from the BRISA cohort. Methods: This was a longitudinal study based on data from the Brazilian Ribeirão Preto and São Luís Birth Cohort Studies (BRISA), referring to São Luís (MA). The study included girls born in 2010 who participated in all three waves of the cohort and had information on menarche occurrence and age. After excluding male participants, the final sample consisted of 768 adolescents. Early menarche was defined as occurrence before 12 years of age. Descriptive analyses, inverse probability weighting to adjust for differential losses, and path analysis for the mediation model were performed using RStudio and Mplus software. Results: Birth weight showed no direct effect on early menarche (CP = 0.00; p = 0.999) and no indirect effect mediated by BMI at 13–34 months (CP = 0.035; p = 0.318). There was also no direct effect of birth weight on BMI-for-age in early childhood (CP = 0.237; p = 0.282). Maternal early menarche (CP = 0.18; p < 0.001) and early childhood BMI (CP = 0.15; p = 0.013) had direct and positive effects on early menarche. Gestational weight gain, socioeconomic class, intrauterine growth restriction, gestational age, skin color, and asthma showed no significant effects (p > 0.05). Conclusion: Birth weight showed no direct or indirect effect on early menarche. In contrast, BMI in early childhood and maternal early menarche were positively associated with the outcome, reinforcing the importance of early-life nutritional status as a determinant of pubertal development.