Assessing bone development in preterm infants using quantitative ultrasonography showed a decline in the early postnatal period

Aim: Preterm infants have an insufficient bone mineral store at birth and this study explored their bone development during the early postnatal period. Methods: The metacarpal speed of sound (mcSOS) and metacarpal bone transmission time (mcBTT) were used to assess bone development in 277 preterm infants, admitted to the neonatal intensive care unit of the VU University Medical Center, Amsterdam, the Netherlands from 2007-2012. Results: During the first nine postnatal weeks, the mcSOS declined from 10 to 38 m per second per week and the mcBTT declined from 20 to 71 nanoseconds per week. The pattern of change in both of these measurements showed a significant difference between infants born before 32 weeks of gestation (p = 0.048) and those born between 28 and 32 weeks of gestation (p = 0.008). There was a borderline significant difference in the pattern of change of the mcBTT in infants with a protein intake below 2 g/kg per day versus a higher intake (p = 0.050). Conclusion: The mcSOS and mcBTT of preterm infants showed a small to moderate decline during the early postnatal period. Future studies should explore the clinical relevance of this decline and develop interventions to halt it.