title: Extreme winter temperature and birth defects: a population-based case-control study.
abstract: OBJECTIVE
  We examined the relationship between extreme winter temperatures and birth defects to determine whether pregnant women might be vulnerable to the weather extremes expected with climate change.
  
  
  METHODS
  In this population-based, case-control study, we linked the New York State Congenital Malformations Registry to birth certificates (1992-2006). Cases were defined as live births with birth defects, and controls were selected from a 10% random sample of live births. We assigned meteorological data based on maternal birth residence and summarized universal apparent temperature across gestational weeks 3-8 (embryogenesis). We defined an extreme cold day as a day with mean temperature below the 10th percentile of the regional winter temperature distribution and a cold spell as 3 consecutive extreme cold days. We averaged temperature for each week of the first trimester to identify susceptible periods. We estimated adjusted odds ratios (ORs) and 95% confidence intervals (CIs) with multivariable logistic regression for 30 birth defects groups.
  
  
  RESULTS
  Among 13,044 cases and 59,884 controls with at least 1 week of embryogenesis in winter, coarctation of the aorta was associated with a 1°C decrease in mean universal apparent temperature (OR 1.06, 95% CI 1.02-1.11), cold spell (OR 1.61, 95% CI 1.11-2.34), and number of extreme cold days. We observed reduced odds of hypoplastic left heart syndrome and dislocated hip for some cold indicators.
  
  
  CONCLUSIONS
  Most birth defects were not associated with cold indicators; however, we found positive associations between cold indicators and coarctation of the aorta in the biologically-relevant developmental window which warrants replication.
authors.affiliation: New York State Department of Health, Bureau of Environmental & Occupational Epidemiology, Empire State Plaza, Corning Tower, Room 1203, Albany, NY 12237, United States; University at Albany, School of Public Health, Department of Epidemiology & Biostatistics, One University Place, Rensselaer, NY 12144, United States.
authors.forename: Alissa R
authors.initials: AR
authors.lastname: Van Zutphen
authors.affiliation: New York State Department of Health, Bureau of Environmental & Occupational Epidemiology, Empire State Plaza, Corning Tower, Room 1203, Albany, NY 12237, United States; University at Albany, School of Public Health, Department of Epidemiology & Biostatistics, One University Place, Rensselaer, NY 12144, United States.
authors.forename: Wan-Hsiang
authors.initials: WH
authors.lastname: Hsu
authors.affiliation: New York State Department of Health, Bureau of Environmental & Occupational Epidemiology, Empire State Plaza, Corning Tower, Room 1203, Albany, NY 12237, United States; University at Albany, School of Public Health, Department of Epidemiology & Biostatistics, One University Place, Rensselaer, NY 12144, United States. Electronic address: sxl05@health.state.ny.us.
authors.forename: Shao
authors.initials: S
authors.lastname: Lin
mesh_terms: D000328:Adult; D001017:Aortic Coarctation / Q000453:epidemiology*; D016022:Case-Control Studies; D003080:Cold Temperature / Q000009:adverse effects*; D047108:Embryonic Development; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009518:New York / Q000453:epidemiology; D011247:Pregnancy
keywords: Birth defects; CI; Climate change; Cold; OR; Temperature; Winter; confidence interval; odds ratio