Bone mineral content of appropriate and light for gestational age preterm and term newborn infants.

Bone mineral content was measured by single photon absorptiometry at the right mid humerus of 122 appropriate and 35 light for gestational age newborn infants born after 26 to 42 weeks of gestation. Bone mineral content was 2.4 times greater at the mid humerus than at the distal radius. Even in extremely low birth weight infants reproducible measurements were possible at the mid humerus. Light for gestational age infants showed a lower bone mineral content than appropriate for gestational age infants when bone mineral content was related to gestational age. When related to birthweight (g) bone mineral content showed a similar linear relationship in light for gestational age (mg/cm = 44.2 + 0.037 weight) and appropriate for gestational age (mg/cm = 39.4 + 0.040 weight) infants. For all 177 infants the relationship was mg/cm = 32.3 + 0.045 weight (r = 0.91). It is concluded that in growing preterm infants bone mineral content should be assessed in relation to weight rather than to age.