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

Adolescence is a critical time for skeletal growth and mineralization. Expo sure to protective or detrimental factors during this period may influence peak bone mass attainment and subsequent development of osteoporosis. In or der to evaluate the association of body size during adolescence with subseq uent adult bone mass, we conducted a follow-up study of a community-based c ohort 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 fo r current adult weight and other factors related to bone mass, weight at me narche was found to be positively associated with subsequent adult BMD. Sim ilarly, body mass index (BMI) at menarche was positively associated with ad ult BMD. In contrast, age at menarche was not found to predict adult BMD. W hen the subjects were divided into quartiles based on their BMI at menarche , subjects in the lowest quartile of BM at menarche had adult mean BMD that was 8-15% lower at the measured sites compared with subjects in the highes t quartile of BMI at menarche. In conclusion, low body weight and low BMI a t menarche appear to be significant predictors of reduced bone mass in heal thy premenopausal women ages 40-45 years.