Association between age at menarche and bone mineral density in postmenopausal women

Age at menarche (AAM) directly affects female estrogen levels, which play a vital role in bone metabolism. The exact relationship between bone mineral density (BMD) and AAM remains controversial. Thus, this study aimed to determine the association between AAM and lumbar spine (LS) BMD in postmenopausal women.

Our data were based on the National Health and Nutrition Examination Survey (NHANES) 2011-2018. AAM was divided into three categories including ≤ 12, 13-15, and ≥ 16 years, and the ≤ 12 years old category was used as the reference group. To examine the association between AAM and LS BMD, we used three weighted linear regression models, Model 1 (without adjustment), Model 2 (with adjustment for age, race, and body mass index [BMI]), and Model 3 (with adjustment for all covariates).

This study included 1195 postmenopausal women aged 40-59 years. In the unadjusted model, a menarche age of ≥ 16 years compared with a menarche age of ≤ 12 years was associated with lower LS BMD (β = - 0.083, 95% CI - 0.117, - 0.048, P < 0.001). After adjusting for potential confounding factors, there was still a negative correlation in model 2 (β = - 0.078, 95% CI - 0.113, - 0.042, P < 0.001) and model 3 (β = - 0.065, 95% CI - 0.096, - 0.033, P < 0.001). Moreover, this significant relationship persisted after excluding participants who used female hormones (β = - 0.053, 95% CI - 0.089, - 0.016, P = 0.006).

Our study found that postmenopausal women with a menarche age of ≥ 16 years had significantly lower LS BMD than that had by those with a menarche age of ≤ 12 years. As a result of this study, postmenopausal women with a late menarche age may have a higher risk of lumbar osteoporotic fractures and need better bone health care.