Effect of Vitamin D Deficiency on Bone Mineral Density of Healthy Newborns relative to their Weight

Background: Vitamin D is required for normal bone growth and mineralization. We aimed to determine if there is any relation between vitamin D deficiency and bone density of healthy newborns. Methods: Plasma 25-hydroxy vitamin D (25OHd) was measured in sixty healthy mothers and their newborn term infants as an indicator of vitamin D status. In their infants, anthropometry and (BMD) Bone mineral density of right wrist was measured within the first ten days of delivery. All mothers completed a 24 hour recall and 3-day food and supplement record. Vitamin D status of mothers and infants was classified as deficient or adequate and then we compared infant bone mass in these groups using non-paired Mest. Maternal and infant variables known to be related to bone mass were tested for their relation to BMD using regression analysis. Results: Twenty four (40%) of the mothers and 18 (30%) of the infants had low plasma 25 hydroxy vitamin D. Infants who were vitamin D deficient were larger at birth and followup. Absolute femur bone mineral density was different between adequate vitamin D infant group and vitamin D deficient group in spite of larger body size in the later group. By regression analysis, right wrist bone density was associated with greater gestational age and weight at birth as well as higher infant plasma 25 (OH) D. Conclusion: A high rate of vitamin D deficiency was observed among women and their newborn infants. Vitamin D deficiency in infants was associated with greater weight and length but lower bone mass relative to body weight. Further studies are needed to determine if fortification of formula to normalize vitamin D status would reset the BMD status.