title: Occupational factors and risk of preterm birth in nurses.
abstract: OBJECTIVE
  We evaluated first-trimester exposures and the risk of preterm birth in the most recent pregnancy of participants of the Nurses' Health Study II.
  
  
  METHODS
  Log binomial regression was used to estimate the relative risk (RR) for preterm birth in relation to occupational risk factors, such as work schedule, physical factors, and exposures to chemicals and x-rays, adjusted for age and parity.
  
  
  RESULTS
  Part-time work (<or= 20 hours a week) was associated with a lower risk of preterm birth [RR, 0.7; 95% confidence interval [CI], 0.6-0.9]. Working nights was associated only with early preterm birth (< 32 weeks of gestation) (RR, 3.0; 95% CI, 1.4-6.2). Although based on only 11 exposed preterm cases, self-reported exposure to sterilizing agents was associated with an increased risk (RR, 1.9; 95% CI, 1.1-3.4).
  
  
  CONCLUSIONS
  These data suggest that night work may be related to early but not late preterm birth, whereas physically demanding work did not strongly predict risk.
authors.affiliation: National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, OH 45226, USA. clawson@cdc.gov
authors.forename: Christina C
authors.initials: CC
authors.lastname: Lawson
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Whelan
authors.forename: Eileen N
authors.initials: EN
authors.lastname: Hibert
authors.forename: Barbara
authors.initials: B
authors.lastname: Grajewski
authors.forename: Donna
authors.initials: D
authors.lastname: Spiegelman
authors.forename: Janet W
authors.initials: JW
authors.lastname: Rich-Edwards
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006801:Humans; D009726:Nurses; D009784:Occupational Diseases / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D016017:Odds Ratio; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D047928:Premature Birth / Q000209:etiology*; D012307:Risk Factors