Age at menarche and general and abdominal obesity in older Brazilian women: ELSI-Brazil.

Objective: To examine the association between age at menarche and general and/or abdominal obesity in Brazilian women aged ≥ 50 years.

Methods: Cross-sectional study conducted with data from the second wave of the Brazilian Longitudinal Study of Aging (Estudo Longitudinal da Saúde dos Idosos Brasileiros(ELSI-Brazil, 2019-2021), in a nationally representative sample of community-dwelling individuals aged ≥ 50 years. Self-reported age at menarche was categorized as ≤ 12 years, 13-15 years, and ≥ 16 years. General obesity was defined as a body mass index of ≥ 30 kg/m2, and abdominal obesity as a waist circumference of ≥ 88 cm. The variables were combined into "general or abdominal obesity" and "general and abdominal obesity". Multinomial logistic regression adjusted for sociodemographic and lifestyle characteristics was used.

Results: Among the 4,229 participants, 41.1% (95% confidence interval -95%CI 37.9-44.3) reported menarche at ≤ 12 years and 9.3% (95%CI 8.0-10.9) at ≥ 16 years. The prevalence of general or abdominal obesity was 36.6% (95%CI 33.7-39.5), while the prevalence of general and abdominal obesity was 35.0% (95%CI 32.5-37.7). After adjustments, women with age at menarche of ≤ 12 and 13-15 years had, respectively, 84% (odds ratio - OR = 1.84; 95%CI 1.14-2.98) and 64% (OR = 1.64; 95%CI 1.04-2.57) greater odds of general and abdominal obesity compared with those with menarche at ≥ 16 years. There was no significant association between age at menarche and general or abdominal obesity.

Conclusion: Menarche before age 16 is associated with a higher odds of general and abdominal obesity combined, but not in isolation, suggesting its potential as a relevant marker for the formulation of public policies aimed at preventing obesity in girls from school age onwards.