title: Stillbirth risk factors according to timing of exposure.
abstract: OBJECTIVE
  The purpose of the present study is to identify risk factors for stillbirth and explore hypotheses about the cause of stillbirth based on the time in gestation when exposures occur.
  
  
  METHODS
  Relationships between lifestyle factors, pregnancy conditions, medication use, and occupation on risk for stillbirth were examined within a population-based case-control study. Women who had a stillbirth and a random sample of women who had a live birth between 1999 and 2001 were identified through perinatal databases in Nova Scotia and Eastern Ontario, Canada. Exposure data were collected for each month of pregnancy and analyzed within trimesters. Case-control data were converted to case-cohort data, and hazard ratios (HRs) and 95% confidence intervals (CIs) were determined from Cox proportional hazards models.
  
  
  RESULTS
  This study included 105 stillbirth cases and 389 live-birth controls. Fertility treatment in the present pregnancy was associated with increased risk for stillbirth (adjusted HR, 4.0; 95% CI, 1.4-11.6). Smoking during the first trimester also was associated with increased risk for stillbirth (adjusted HR, 2.4; 95% CI, 1.2-4.9). Other risk factors included antiemetic use during the first trimester, second-trimester antibiotic use, low family income, and age older than 35 years.
  
  
  CONCLUSIONS
  Risk factors identified in this study concur with findings of previous studies and support the importance of early pregnancy exposures on stillbirth risk.
authors.affiliation: Department of Obstetrics and Gynaecology, Dalhousie University, Halifax, Nova Scotia, Canada. l.dodds@dal.ca
authors.forename: Linda
authors.initials: L
authors.lastname: Dodds
authors.forename: Will D
authors.initials: WD
authors.lastname: King
authors.forename: Deshayne B
authors.initials: DB
authors.lastname: Fell
authors.forename: B Anthony
authors.initials: BA
authors.lastname: Armson
authors.forename: Alexander
authors.initials: A
authors.lastname: Allen
authors.forename: Carl
authors.initials: C
authors.lastname: Nimrod
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008019:Life Style; D050498:Live Birth; D018811:Maternal Exposure / Q000009:adverse effects* / Q000706:statistics & numerical data; D009790:Occupations / Q000706:statistics & numerical data; D011247:Pregnancy; D011256:Pregnancy Outcome; D012307:Risk Factors; D050497:Stillbirth / Q000453:epidemiology*