title: Prediction of survival for preterm births by weight and gestational age: retrospective population based study.
abstract: OBJECTIVE
  To produce current data on survival of preterm infants.
  
  
  METHODS
  Retrospective population based study.
  
  
  METHODS
  Trent health region.
  
  
  METHODS
  All European and Asian live births, stillbirths, and late fetal losses from 22 to 32 weeks' gestation, excluding those with major congenital malformations, in women resident in the Trent health region between 1 January 1994 and 31 December 1997.
  
  
  METHODS
  Birth weight and gestational age specific survival for both European and Asian infants (a) known to be alive at the onset of labour, and (b) admitted for neonatal care.
  
  
  RESULTS
  738 deaths occurred in 3760 infants born between 22 and 32 weeks' gestation during the study period, giving an overall survival rate of 80.4%. The survival rate for the 3489 (92.8%) infants admitted for neonatal care was 86.6%. For European infants known to be alive at the onset of labour, significant variations in gestation specific survival by birth weight emerged from 24 weeks' gestation: survival ranged from 9% (95% confidence interval 7% to 13%) for infants of birth weight 250-499 g to 21% (16% to 28%) for those of 1000-1249 g. At 27 weeks' gestation, survival ranged from 55% (49% to 61%) for infants of birth weight 500-749 g (below the 10th centile) to 80% (76% to 85%) for those of 1250-1499 g. Infants who were large for dates (>/=27 weeks' gestation) had a slightly reduced, but not significant, predicted survival. Similar survival rates were observed for Asian infants. The odds ratio for the survival of infants from a multiple birth compared with singleton infants was 1.4 (1.1 to 1.8). Survival graphs for infants admitted for neonatal care are presented by sex.
  
  
  CONCLUSIONS
  Easy to use birth weight and gestational age specific predicted survival graphs for preterm infants facilitate decision making for clinicians and parents. It is important that these graphs are representative, are produced for a geographically defined population, and are not biased towards the outcomes of particular centres. Such graphs, produced in two stages, allow for the changing pattern of survival of infants from the start of the intrapartum period to immediately after admission for neonatal care.
authors.affiliation: Department of Epidemiology, Leicester University Medical School, Leicester LE1 6TP. msn@le.ac.uk
authors.forename: E S
authors.initials: ES
authors.lastname: Draper
authors.forename: B
authors.initials: B
authors.lastname: Manktelow
authors.forename: D J
authors.initials: DJ
authors.lastname: Field
authors.forename: D
authors.initials: D
authors.lastname: James
mesh_terms: D001208:Asia / Q000208:ethnology; D001724:Birth Weight; D004739:England / Q000453:epidemiology; D005060:Europe / Q000208:ethnology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007752:Obstetric Labor, Premature / Q000208:ethnology / Q000401:mortality*; D011247:Pregnancy; D012189:Retrospective Studies; D016019:Survival Analysis