title: Ossification of sacral vertebral bodies in neonates born 24 to 38 weeks' gestational age and its relevance to spinal ultrasonography.
abstract: OBJECTIVE
  Determination of gestational age and/or birth weight at which sacral ossification centers appear.
  
  
  METHODS
  Radiographs were reviewed of newborns admitted to Auckland City Hospital between January 2008 and December 2010. Infants were divided into weight clusters increasing in 100-g increments from 400 g to 3000 g and 500-g increments thereafter, for a total of 29 weight clusters. Adequate images were available for at least five newborns per cluster.
  
  
  RESULTS
  Images of 163 newborns were reviewed. All but six newborns had five sacral ossification centers by 32 weeks' gestation and a birth weight of 1800 g. Five of the six infants had a congenital anomaly and associated growth restriction.
  
  
  CONCLUSIONS
  Infants can be expected to have all five sacral ossification centers present by the time they reach a gestational age of 32 weeks and/or a birth weight of 1800 g. Variation from this can be associated with congenital anomalies and growth restriction.
authors.affiliation: Newborn Services, Auckland City Hospital, Auckland, New Zealand. elzac@adhb.govt.nz
authors.forename: Elza
authors.initials: E
authors.lastname: Cloete
authors.forename: Malcolm R
authors.initials: MR
authors.lastname: Battin
authors.forename: Farhad B
authors.initials: FB
authors.lastname: Imam
authors.forename: Rita L
authors.initials: RL
authors.lastname: Teele
mesh_terms: D001724:Birth Weight; D003050:Coccyx / Q000502:physiology; D005260:Female; D005865:Gestational Age; D006801:Humans; D008297:Male; D010012:Osteogenesis / Q000502:physiology*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second / Q000502:physiology; D011263:Pregnancy Trimester, Third / Q000502:physiology; D011859:Radiography; D012447:Sacrum / Q000502:physiology*; D013131:Spine / Q000000981:diagnostic imaging*; D014463:Ultrasonography