title: Estimating gestational age at birth: a population-based derivation-validation study.
abstract: BACKGROUND
  Information on newborn gestational age (GA) is essential in research on perinatal and infant health, but it is not always available from administrative databases. We developed and validated a GA prediction model for singleton births for use in epidemiological studies.
  
  
  METHODS
  Derivation of estimated GA was calculated based on 130 328 newborn infants born in Ontario hospitals between 2007 and 2009, using linear regression analysis, with several infant and maternal characteristics as the predictor (independent) variables. The model was validated in a separate sample of 130 329 newborns.
  
  
  RESULTS
  The discriminative ability of the linear model based on infant birth weight and sex was reasonably approximate for infants born before the 37th week of gestation (r2 = 0.67; 95% CI: 0.65-0.68), but not for term births (37-42 weeks; r2 = 0.12; 95% CI: 0.12-0.13). Adding other infant and maternal characteristics did not improve the model discrimination.
  
  
  CONCLUSIONS
  Newborn gestational age before 37 weeks can be reasonably approximated using locally available data on birth weight and sex.
authors: Centre for Research on Inner City Health, The Keenan Research Centre of the Li Ka Shing Knowledge Institute, St Michael's Hospital, Toronto, Ontario, Canada.
authors: M L
authors: ML
authors: Urquia
authors: T A
authors: TA
authors: Stukel
authors: K
authors: K
authors: Fung
authors: R H
authors: RH
authors: Glazier
authors: J G
authors: JG
authors: Ray
mesh_terms: D001724:Birth Weight; D016021:Epidemiologic Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D009864:Ontario; D015203:Reproducibility of Results; D012737:Sex Factors