Weight and body mass index at menarche are associated with premenopausal bone mass

Adolescence is a critical time for skeletal growth and mineralization. Exposure to protective or detrimental factors during this period may influence peak bone mass attainment and subsequent development of osteoporosis. In order to evaluate the association of body size during adolescence with subsequent adult bone mass, we conducted a follow-up study of a community-based cohort of girls who participated in a growth and sexual maturation study 30 years ago. Data from the original study included age at menarche, height at menarche and weight at menarche. Follow-up evaluation of 119 subjects, now premenopausal women ages 40-45 years, included bone mineral density (BMD) measurements of the total body, lumbar spine, femoral neck, total hip, and ultradistal radius by dual-energy X-ray absorptiometry. After adjustment for current adult weight and other factors related to bone mass, weight at menarche was found to be positively associated with subsequent adult BMD. Similarly, body mass index (BMI) at menarche was positively associated with adult BMD. In contrast, age at menarche was not found to predict adult BMD. When the subjects were divided into quartiles based on their BMI at menarche, subjects in the lowest quartile of BMI at menarche had adult mean BMD that was 8-15% lower at the measured sites compared with subjects in the highest quartile of BMI at menarche. In conclusion, low body weight and low BMI at menarche appear to be significant predictors of reduced bone mass in healthy premenopausal women ages 40-45 years.