RT Journal Article SR Electronic T1 Vitamin D in the Newborn, Part I: Assessment of Status and Deficiency Risk Factors JF NeoReviews JO NeoReviews FD American Academy of Pediatrics SP e187 OP e192 DO 10.1542/neo.15-5-e187 VO 15 IS 5 A1 Mimouni, Francis B. YR 2014 UL http://neoreviews.aappublications.org/content/15/5/e187.abstract AB Abbreviations:1,25OH2D, 1α-25-dihydroxycholecalciferol25OHD, 25-hydroxyvitam DAAP, American Academy of PediatricsNIH, National Institutes of HealthPTH, parathyroid hormoneSince 2008, the American Academy of Pediatrics (AAP) has published three documents related to vitamin D requirements of term and preterm infants. The need for developing and updating such guidelines emphasizes the importance of vitamin D not only as an essential element of bone health but also as a nutrient and prohormone that plays an increasingly recognized role in many other organ systems. In this review, we describe: (1) the main circulating metabolites of vitamin D; (2) the significance of their respective blood concentrations during the assessment of vitamin D status; and (3) the factors that influence vitamin D status at birth and the risk factors for neonatal vitamin D deficiency. In a separate article, we discuss the evidence for current vitamin D dietary recommendations in term neonates and delineate the role of vitamin D deficiency in the pathogenesis of osteopenia of prematurity.