[Relationship between age at menarche and obesity in women]

Objective: To explore the relationship between age at menarche and general obesity (based on BMI) and central obesity (based on WC or WHtR) in middle-aged and elderly women in China. Methods: A total of 6 363 women from the China Health and Retirement Longitudinal Study were included. Restricted cubic splines based on binary logistic regressions were used to analyze the relationship between age at menarche and the risk of obesity. Age at menarche was divided into four groups: ≤13, 14- (control group), 16- , and ≥18 years old. Binary logistic regressions were applied to analyze the relationship between the continuous or grouped variable of age at menarche and the risk of obesity. Results: After adjusting potential confounders, the age at menarche showed a negative linear relationship with the risk of general obesity and central obesity. The risk for obesity based on BMI, WC and WHtR significantly decreased by 6% (OR=0.94, 95%CI: 0.90-0.99), 4% (OR=0.96, 95%CI: 0.92-1.00), and 6% (OR=0.94, 95%CI: 0.90-0.99) for each 1 year increase in age at menarche. Compared with participants who had menarche at age 14- years old, the risk for obesity based on BMI (OR=0.71, 95%CI: 0.55-0.91), WC (OR=0.75, 95%CI: 0.62-0.92) and WHtR (OR=0.76, 95%CI: 0.61-0.96) significantly decreased by 29%, 25%, and 24% in participants who had menarche at age ≥18 years old. Conclusions: There was a negative linear relationship between age at menarche and the risk for general obesity and central obesity in middle-aged and elderly women in China. Older age at menarche might be negatively associated with risk for obesity in middle-aged and elderly women.