title: Customised birthweight models: do they increase identification of at-risk infants?
abstract: OBJECTIVE
  The study aims to describe the cohort of women and babies who are classified as small-for-gestational age (SGA) at term by both an Australian customised birthweight model (CBM) and a commonly used population-based standard, and to investigate and compare the utility of these models in identifying babies at risk of experiencing adverse outcomes
  
  
  METHODS
  Routinely collected data on 54 890 singleton-term births at the Mater Mothers' Hospitals, Brisbane, with birthweight less than 4000 g between January 1997 and December 2008, was extracted. Each birth was classified as SGA (<10th centile) or not SGA by either and/or both methods: population-based standards (SGApop ) and CBM (SGAcust ). Babies classified as SGApop , SGAcust or SGAboth were compared with those not classified as SGA by both methods using relative risk and 95% confidence interval, and those only classified as SGAcust were compared with those only classified as SGApop . Maternal demographics, maternal risk factors for fetal growth restriction, pregnancy and labour complications and adverse neonatal outcomes are reported.
  
  
  RESULTS
  A total of 4768 (8.7%) births were classified as SGApop , while 6479 (11.8%) were SGAcust of whom 4138 (63.9%) were also classified as SGApop . Maternal risk factors such as smoking and hypertension were statistically higher for the SGAcust group when compared with SGApop . For the majority of adverse neonatal outcomes, a trend was noted to increased identification using the CBM.
  
  
  CONCLUSIONS
  The CBM provides a modest improvement when compared to a population-based standard to identity term infants at birth who are at risk of adverse neonatal outcomes.
authors.affiliation: Clinical Research Support Unit, Mater Medical Research Institute, South Brisbane, QLD, Australia. kgibbons@mmri.mater.org.au
authors.forename: Kristen
authors.initials: K
authors.lastname: Gibbons
authors.forename: Allan
authors.initials: A
authors.lastname: Chang
authors.forename: Vicki
authors.initials: V
authors.lastname: Flenady
authors.forename: Kassam
authors.initials: K
authors.lastname: Mahomed
authors.forename: Glenn
authors.initials: G
authors.lastname: Gardener
authors.forename: Peter H
authors.initials: PH
authors.lastname: Gray
authors.forename: Michael
authors.initials: M
authors.lastname: Beckmann
authors.forename: Dominique
authors.initials: D
authors.lastname: Rossouw
mesh_terms: D000328:Adult; D001724:Birth Weight; D005260:Female; D005317:Fetal Growth Retardation / Q000175:diagnosis*; D006801:Humans; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases; D007236:Infant, Small for Gestational Age; D008297:Male; D007744:Obstetric Labor Complications; D011247:Pregnancy; D011248:Pregnancy Complications; D012016:Reference Values; D047929:Term Birth