title: Infant mortality at term in Canada: Impact of week of gestation.
abstract: Infants born at term have low mortality, but risk may vary from week to week. We determined the risk of infant mortality at term by gestational week and cause.
  
  
  
  We analyzed 4.1 million infants born at ≥37weeks of gestation in Canada from 1991 to 2010, followed for mortality the first year of life. We estimated hazard ratios (HR) and 95% CIs for early, late and post neonatal mortality from 37 through 41weeks of gestation, adjusting for individual characteristics. The main outcomes were mortality due to congenital anomaly, asphyxia, immaturity, infection, sudden infant death, and injury.
  
  
  
  Infant mortality decreased progressively from 4.55 per 1000 at 37weeks to 1.62 per 1000 at 41weeks. Early neonatal mortality varied little between 39 and 41weeks, but post neonatal mortality was lowest at 40-41weeks. Relative to 41weeks of gestation, mortality at 39weeks was higher for congenital anomaly (HR 1.30, 95% CI 1.05-1.60) and sudden infant death (HR 1.58, 95% CI 1.18-2.11).
  
  
  
  In Canada, mortality at term is lowest for infants born at 40 or 41weeks of gestation, especially at late and post neonatal ages, and for congenital anomaly and sudden infant death.
authors.affiliation: Institut national de santé publique du Québec, 190 Cremazie E. Blvd., Montreal, Quebec H2P 1E2, Canada; University of Montreal Hospital Research Centre, 900 Rue Saint-Denis, Montreal, Quebec H2X 0A9, Canada; Department of Social and Preventive Medicine, University of Montreal, 7101, Parc Ave., Montreal, Quebec H3N 1X9, Canada. Electronic address: nathalie.auger@inspq.qc.ca.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Auger
authors.affiliation: Department of Social and Preventive Medicine, University of Montreal, 7101, Parc Ave., Montreal, Quebec H3N 1X9, Canada; Maternal and Infant Health Section, Public Health Agency of Canada, 785 Carling Ave, Ottawa, Ontario K1A 0K9, Canada.
authors.forename: Nicolas L
authors.initials: NL
authors.lastname: Gilbert
authors.affiliation: Department of Epidemiology, Biostatistics and Occupational Health, McGill University, 1020 Pine Ave. West, Montreal, Quebec H3A 1A2, Canada.
authors.forename: Jay S
authors.initials: JS
authors.lastname: Kaufman
mesh_terms: D000328:Adult; D002170:Canada / Q000453:epidemiology; D000013:Congenital Abnormalities / Q000401:mortality; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007226:Infant Mortality; D007231:Infant, Newborn; D008423:Maternal Age; D016016:Proportional Hazards Models; D012307:Risk Factors; D013398:Sudden Infant Death / Q000453:epidemiology; D047929:Term Birth
keywords: Gestational age; Infant mortality; Term birth