title: Seasonal variation in fetal growth: accounting for sociodemographic, biological, and environmental exposures.
abstract: OBJECTIVE
  We sought to investigate seasonal variation in fetal growth, accounting for important sociodemographic, biological, and environmental exposures.
  
  
  METHODS
  Records of births 1998 through 2006 in Perth, Western Australia were obtained (N = 147,357). We investigated small for gestational age and sex and the proportion of optimal birthweight (POBW) in relation to seasonal exposures (season, temperature, sunlight) by trimester of pregnancy. Adjustment was made for a wide range of risk factors.
  
  
  RESULTS
  The POBW for neonates with third trimesters predominantly in summer was 0.18% (0.00-0.36%) lower than for those in winter. POBW decreased by 0.14% (0.01-0.27%) per interquartile range increase in third-trimester temperature (9.15°C). An interquartile range increase in temperature over pregnancy (0.73°C) was associated with an odds ratio of 1.02 (95% confidence interval, 1.00-1.05) for small for gestational age and sex.
  
  
  CONCLUSIONS
  Reduced fetal growth was associated with elevated ambient temperatures throughout and late in pregnancy, independently of air pollution and other risk factors.
authors: School of Population Health, The University of Western Australia, Crawley, Sydney, New South Wales, Australia. gavin.pereira@uwa.edu.au
authors: Gavin
authors: G
authors: Pereira
authors: Angus
authors: A
authors: Cook
authors: Fatima
authors: F
authors: Haggar
authors: Carol
authors: C
authors: Bower
authors: Natasha
authors: N
authors: Nassar
mesh_terms: D001724:Birth Weight; D004781:Environmental Exposure / Q000009:adverse effects / Q000706:statistics & numerical data*; D005260:Female; D047109:Fetal Development / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D008297:Male; D012307:Risk Factors; D012621:Seasons; D012959:Socioeconomic Factors; D014904:Western Australia / Q000453:epidemiology