title: Birth weight percentile and the risk of term perinatal death.
abstract: OBJECTIVE
  To estimate the association between birth weight percentile and the risk of perinatal death at term in relation to the cause of death.
  
  
  METHODS
  We performed a retrospective cohort study of all term singleton births in delivery units in Scotland between 1992 and 2008 (n=784,576), excluding perinatal deaths ascribed to congenital anomaly.
  
  
  RESULTS
  There were 1,700 perinatal deaths in the cohort, which were not the result of congenital anomaly (21.7/10,000 women at term). We observed a reversed J-shaped association between birth weight percentile and the risk of antepartum stillbirth in all women, but the associations significantly differed (P<.001) according to smoking status. The highest risk (adjusted odds ratio referent to 21st-80th percentile, 95% confidence interval) among nonsmokers was for birth weight third or less percentile (10.5, 8.2-13.3), but there were also positive associations for birth weight percentiles 4th-10th (3.8, 3.0-4.8), 11th-20th (1.9, 1.5-2.4), and 98th-100th (1.8, 1.3-2.4). Among smokers, the associations with being small were weaker and the associations with being large were stronger. We also observed a reversed J-shaped association between birth weight percentile and the risk of delivery-related perinatal death (ie, intrapartum stillbirth or neonatal death), but there was no interaction with smoking. The highest risk was for birth weight greater than the 97th percentile (2.3, 1.6-3.3), but there were also associations with third or less percentile (2.1, 1.4-3.1), 4th-10th (1.8, 1.4-2.4), and 11th-20th (1.5, 1.2-2.0). Analysis of the attributable fraction indicated that approximately one in three antepartum stillbirths and one in six delivery-related deaths at term could be related to birth weight percentile outside the range 21st-97th percentile.
  
  
  CONCLUSIONS
  Effective detection of variation in fetal size at term has potential as a screening test for the risk of perinatal death.
  
  
  METHODS
  II.
authors.affiliation: Departments of Obstetrics and Gynaecology and Public Health and Primary Care, University of Cambridge, and the National Institute for Health Research Cambridge Comprehensive Biomedical Research Centre, Cambridge, and the Institute of Health and Wellbeing, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Alexandros A
authors.initials: AA
authors.lastname: Moraitis
authors.forename: Angela M
authors.initials: AM
authors.lastname: Wood
authors.forename: Michael
authors.initials: M
authors.lastname: Fleming
authors.forename: Gordon C S
authors.initials: GCS
authors.lastname: Smith
mesh_terms: D000328:Adult; D001724:Birth Weight; D002423:Cause of Death; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D054238:Perinatal Mortality; D011247:Pregnancy; D012189:Retrospective Studies; D018570:Risk Assessment; D012606:Scotland / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology; D050497:Stillbirth / Q000453:epidemiology*; D055815:Young Adult