Socioeconomic status over the life-course and adult bone mineral density: the Midlife in the U.S. Study.

PURPOSE Adult bone mass depends on acquisition in childhood and decline in adulthood, and may be influenced by socioeconomic conditions over the entire life course. METHODS We examined associations of bone mineral density (BMD) in adulthood with life course socioeconomic status in 729 participants in the Midlife in the United States Biomarker Project, adjusting for age, menopausal transition stage, race, gender, body weight, smoking, physical activity in several life stages, and research site. Primary predictors were a) childhood socioeconomic advantage score (including parental education, self-rated financial status relative to others, not being on welfare), b) adult education level (no college vs. some college vs. college graduate), and c) adult current financial advantage score (including family-adjusted poverty to income ratio, self-assessed current financial situation, having enough money to meet needs, ease in paying bills). RESULTS Mean age was 56.9 (range 34-85) years. After adjustment for covariates, childhood socioeconomic advantage and adult education level were positively associated with lumbar spine BMD: 0.27 standard deviations (SD) higher at 90th compared to 10th percentile of childhood advantage score (P=0.009), and 0.24 SD higher in college graduates compared to participants without college education (P=0.01). Adult current financial advantage was not associated with lumbar spine BMD. None of the three socioeconomic indicators was significantly associated with femoral neck BMD. CONCLUSIONS Childhood socioeconomic advantage and adult education level were associated with higher adult lumbar spine BMD. Current financial advantage was not associated with BMD. Childhood socioeconomic factors may influence acquisition of lumbar BMD.