A survey of bone mineral content and density in full-term and preterm infants

Objectives: Dual energy x-ray absorptiometry (DEXA) is a convenient tool for measurement of bone mineralization. There are no normative data for bone mineral density (BMD) and bone mineral content (BMC) in preterm infants in Taiwan. Hence our purpose in this study was to use DEXA to evaluate and follow up serial changes in bone mineral status in full-term and preterm infants and to establish normative data in this population. Methods: Between July 1999 and November 2000, 47 full-term (gestational age, 38.5±1.3 weeks) and 63 preterm, low-birth-weight infants (gestational age, 29.9±2.4 weeks) were enrolled and categorized into full-term (FT) and preterm (PT) groups. Bone mineral status (density and content) was measured by means of DEXA at a fixed schedule (0-1, 6 and 12 mon). Results: The BMC of the FT and PT groups at 0-1, 6 and 12 mon were as follow: 67.22±16.84 vs 38.87±16.85, 167.72±35.19 vs 155.37±50.78, and 258.67±54.31 vs 274.20±34.10 g. The BMD of the FT and PT groups at the corresponding ages were: 0.31±0.04 vs 0.23±0.05, 0.35±0.02 vs 0.35±0.05, and 0.44±0.03 vs 0.45±0.02 g/cm², respectively. Post-conceptional age and birth length were significant predictors of BMC. Conclusions: The bone mineral status of both groups was established from this study. The BMD and BMC of PT infants had caught up with those of FT infants by 6 and 12 mon.