Bone mineral density of the lumbar spine in very-low-birth-weight infants:a longitudinal study

To examine osteopenia in very low birth weight (VLBW) infants we used repea ted dual-energy X-ray absorptiometry in a prospective study of lumbar spina l bone mineral density (BMD) in Japanese VLBW infants (birthweight 426-1498 g; n = 61, group 1) aged 40 weeks postconception to 3 years of age. Contro l subjects were Japanese infants with birthweight 1500-1999 g (group 2), 20 00-2499 g (group 3), or more than 2500 g (group 4). BMD in group 1 during t he early period after birth was very low, increased rapidly for 1 year, and then gradually increased until 3 years of age (r = 0.931, P < 0.0001). BMD at the age of 40 weeks postconception was 0.085 +/- 0.026, 0.132 +/- 0.039 , 0.178 +/- 0.042, and 0.196 +/- 0.046 g/cm(2) in groups 1, 2, 3, and 4, re spectively (P < 0.0001). However, at 1 and 2 years of age no differences we re observed among the groups in BMD. Conclusion This study shows that lumbar spinal BMD in VLBW infants can norm alize by the age of 2 years.