Birth weight and musculoskeletal health in 36-year-old men and women: results from the Amsterdam Growth and Health Longitudinal Study.

The results of recent epidemiological studies suggest that birth weight is related to adult bone mineral status. Since birth weight might also be related to muscle strength and fat-free mass, which are important determinants of bone health, the aim of this study was to investigate the following: is birth weight related to bone mineral content (BMC) and bone mineral density (BMD) at the lumbar level, at the hip and of the total body, and to structural properties of the heel bone, to fat-free mass (FFM) and to muscle strength, at the age of 36 years? Two hundred and eighty-two subjects (162 women) underwent dual X-ray absorptiometry (DEXA) measurement for the assessment of BMC and BMD at different sites and the FFM and/or measurement of the structural properties of the heel bone, which were estimated with speed of sound (H-SOS) and broadband ultrasound attenuation. Muscle strength was assessed with two fitness tests (static arm-pull, and high jump). Information on birth weight was gathered by means of a questionnaire. The data were analyzed by application of multiple linear regression. Birth weight was positively related to FFM. In a crude model, birth weight was found to be positively associated with BMC, but not after adjustment for adult body weight. No significant associations were found between birth weight and muscle strength or birth weight and BMD. Furthermore, birth weight was inversely related to H-SOS. No other relationships were observed. Results support the fetal origins hypothesis that lower birth weight is related to lower BMC and FFM, but not that birth weight is associated with BMD and muscle strength. Furthermore, FFM was not identified as a link between birth weight and musculoskeletal health.