Enriched post-discharge formula versus term formula for bone strength in very low birth weight infants: a longitudinal pilot study

To initiate a longitudinal pilot study comparing the effect of nutrient-enriched post-discharge formula (PDF) with standard term formula (TF) on bone strength of very low birth weight (VLBW) infants in the first six months post-term.Two matched groups of VLBW infants were randomly assigned to enriched PDF (n=10) or TF (n=10) at corrected age of 40 weeks. Anthropometric measurements of growth and measurements of bone speed of sound (SOS) indicating bone strength and bone turnover markers (bone-specific alkaline phosphatase and cross-linked carboxy terminal telopeptide of type I collagen) were taken at term and at three and six months corrected age.The anthropometric measurements of infants fed PDF and TF were comparable at three and six months corrected age. Bone SOS of the PDF group increased from 2760+/-113 m/s at term to 2877+/-90 m/s and 3032+/-60 m/s at three and six months corrected age, respectively (P0.001). Likewise, bone SOS of the TF group increased from 2695+/-116 m/s at term to 2846+/-72 and 2978+/-83 m/s at three and six months, respectively (P0.001). No statistically significant difference was found between the groups in terms of growth and bone SOS measurements. The levels of both bone turnover markers decreased significantly during the study period (P0.001 for both groups).Feeding with PDF after term had no short-term beneficial effect on bone strength and bone turn-over of VLBW infants.