title: Maternal 25-hydroxyvitamin D level and fetal bone growth assessed by ultrasound: a systematic review.
abstract: OBJECTIVE
  To assess systematically the role of maternal vitamin D levels in fetal bone growth.
  
  
  METHODS
  PubMed, EMBASE and Cochrane databases were searched using the search words [Vitamin D] in combination with [fetal, fetus, intrauterine, or prenatal AND growth, development, bone, femur, or humerus]; [crown-rump length]; or [ultrasonography, prenatal]. Criteria for inclusion in this systematic review were data on maternal serum 25-hydroxyvitamin D (25(OH)D) during pregnancy and measurement of fetal growth by ultrasound.
  
  
  RESULTS
  We identified 750 publications initially, from which five observational studies were selected for inclusion in the final review. The parameters studied were humerus length (HL) and femur length (FL) and their Z-scores, femoral volume, femoral distal metaphyseal cross-sectional area (CSA), femoral proximal metaphyseal diameter (PMD), femoral mid-shaft diameter and crown-rump length. In one study, 25(OH)D was associated directly with FL; in another study 25(OH)D only correlated with FL and HL Z-scores when calcium intake was insufficient. Two studies found no association between 25(OH)D and FL, but detected a direct association with femoral PMD, and an inverse relation with femoral distal metaphyseal CSA, respectively.
  
  
  CONCLUSIONS
  Observational studies investigating the role of maternal vitamin D levels in fetal bone growth are sparse. Their evidence suggests that low maternal 25(OH)D levels may affect fetal bone growth under certain circumstances, especially in cases of simultaneous low calcium intake. Further studies are necessary.
authors.affiliation: Hans Christian Andersen Children's Hospital, Odense University Hospital, Odense, Denmark; Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Galthen-Sørensen
authors.forename: L B
authors.initials: LB
authors.lastname: Andersen
authors.forename: L
authors.initials: L
authors.lastname: Sperling
authors.forename: H T
authors.initials: HT
authors.lastname: Christesen
mesh_terms: D015415:Biomarkers / Q000097:blood; D001846:Bone Development / Q000502:physiology*; D018568:Crown-Rump Length; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000196:embryology*; D047109:Fetal Development / Q000502:physiology*; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging / Q000196:embryology*; D011247:Pregnancy; D016216:Ultrasonography, Prenatal; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: fetal bone formation; fetal growth; intrauterine growth restriction; ultrasound; vitamin D