Bone mineral content and growth in very-low-birth-weight premature infants. Does bronchopulmonary dysplasia make a difference?

It is reported that very-low-birth-weight (VLBW) infants with the complication of bronchopulmonary dysplasia (BPD) are at high risk for metabolic bone disease and growth retardation. In a prospective study, we compared growth and bone mineral content (BMC) during the first year of life in 16 VLBW infants with BPD and 16 VLBW control infants. The BPD and control groups were matched for gestational age (28.2 +/- 0.8 vs 28.4 +/- 1.2 weeks) and birth weight (986 +/- 158 vs 1037 +/- 147 g). Calcium, phosphorus, vitamin D, and energy intakes did not differ during the initial 60-day period of hospitalization. At 1 year of age, there were no significant differences in BMC (104.4 +/- 21.4 vs 109.7 +/- 19.2 mg/cm), weight (7440 +/- 1090 vs 7420 +/- 826 g), length (66.9 +/- 3.4 vs 67.7 +/- 3.0 cm), or head circumference (45.1 +/- 1.5 vs 44.0 +/- 1.0 cm) between BPD and control groups. In both groups bone mineralization was delayed compared to the intrauterine curve for BMC. Growth was also delayed compared to the growth curves of Babson for premature infants during the first year of life. We conclude that for our study population, factors other than the presence or absence of BPD are responsible for marked delays in bone mineralization and growth in VLBW premature infants.