Low total body bone mineral content and high bone resorption in Korean winter-born versus summer-born newborn infants

Abstract

Seasonal differences in newborn total body bone mineral content (TBBMC) have not been studied, particularly in relation to alterations in vitamin D status in winter. In vitamin D deficiency bone resorption may be high and bone mineralization low. Bone resorption may be assessed by serum cross-linked carboxyterminal telopeptide of type I collagen (ICTP) measures. Because vitamin D supplements throughout pregnancy are uncommon in Korea, we hypothesized that in Korean winter newborns, TBBMC is low and serum ICTP high from high bone resorption and low 25-hydroxyvitamin D (25-OHD) compared with those in summer newborns. Seventy-one Korean term infants were studied prospectively in summer (July through September, n = 37) versus winter (January through March, n = 34); TBBMC was measured before 3 days of age by dual-energy x-ray absorptiometry. Significant seasonal differences were found: winter newborns had 6% lower TBBMC (least squares means ± SD; 86.7 ± 7.7 gm vs 93.9 ± 7.8 gm, p = 0.0002), lower cord serum 25-OHD (10.7 ± 8 nm vs 30 ± 15 nm, p = 0.0001) and 1,25-dihydroxyvitamin D, and higher ICTP (96.4 ± 20.3 μg/L vs 74.8 ± 24 μg/L, p = 0.0002) and calcium than summer newborns. TBBMC correlated with serum 25-OHD ( r = 0.243, p = 0.047) and inversely with ICTP ( r = –0.333, p = 0.008). We suggest that in Korea low maternal vitamin D status in winter results in marked reduction in newborn TBBMC. (J Pediatr 1998;132:421-5)