Increments in whole body bone mineral content associated with weight and length in pre-term and full-term infants during the first 6 months of life

Background. The objective of the present study was to assess bone mineral c ontent (BMC) of the whole skeleton in pre-term and full-term healthy infant s and the factors influencing BMC, such as bone area, birth weight, birth l ength, current weight, current length, gender, and gestational age. Methods. Forty-eight healthy full-term infants and 34 healthy premature inf ants fed predominantly with intact human milk were studied. BMC was measure d monthly with dual energy X-ray absorptiometry (DEXA). At the same time, l ength and weight were measured and registered. Pre-term infants were studie d at 60-day intervals. Results. For both full-term and pre-term infants, BMC increased during the first months of life. However, the values of pre-term infants never reached the values of full-term infants, even after correcting for age and weight. For both full-term and pre-term infants, BMC was significantly correlated at the second month with birth weight (r = 0.901), birth length (r = 0.860) , gestational age (r = 0.803), bone area (r = 0.960), current weight (r = 0 .920), and current length (r = 0.840, p <0.001 for all correlation coeffici ents). Multivariate analysis revealed that bone area was the most important factor in predicting BMC. Conclusions. Pre-term children have lower BMC than full-term children. The main factor explaining this apparent osteopenia is bone area. Pre-term chil dren have a higher daily mineralization rate than full-term children, but t his catch-up mineralization is not enough to reach BMC levels seen in full- term children. (C) 2001 IMSS. Published by Elsevier Science Inc.