Objective: To investigate the association between birth weight and bone mineral content (BMC), and whether this relationship differs between men and women.
Methods: A total of 10,159 participants from the ELSA-Brasil cohort were eligible for this analysis. The outcome was the z-score of the ratio BMC (kg)/height (m). The exposure was the low birth weight (< 2.5kg). The magnitude of the associations was estimated by mean differences and their respective 95% confidence intervals (95%CI) using linear regression. All analyses were presented for the total population and stratified by sex.
Results: Most were women (54.98%), and the mean age was 52.72 years (SD ± 6.6). In the crude model, we observed that low birth weight was associated with a lower mean BMC/height z-score, compared to adequate birth weight (mean difference: -0.30; 95%CI: -0.39 to -0.21), and this effect was stronger in men (mean difference: -0.43; 95%CI: -0.56 to -0.30) than in women (mean difference: -0.31; 95%CI: -0.44 to -0.19). After adjusting for age, sex per total population, race/skin color, maternal education, individual education, and current weight, there was a considerable reduction in the magnitude of the association (total population: -0.10; 95%CI: -0.14 to -0.06; men: -0.13; 95%CI: -0.21 to -0.06; women: -0.13; 95%CI: -0.21 to -0.05).
Conclusion: Low birth weight is related to BMC/height z-score in both sexes with no indication of differences by sex. The magnitude of the associations was attenuated after adjustment for the current weight.