title: Miscarriage among flight attendants.
abstract: BACKGROUND
  Cosmic radiation and circadian disruption are potential reproductive hazards for flight attendants.
  
  
  METHODS
  Flight attendants from 3 US airlines in 3 cities were interviewed for pregnancy histories and lifestyle, medical, and occupational covariates. We assessed cosmic radiation and circadian disruption from company records of 2 million individual flights. Using Cox regression models, we compared respondents (1) by levels of flight exposures and (2) to teachers from the same cities, to evaluate whether these exposures were associated with miscarriage.
  
  
  RESULTS
  Of 2654 women interviewed (2273 flight attendants and 381 teachers), 958 pregnancies among 764 women met study criteria. A hypothetical pregnant flight attendant with median first-trimester exposures flew 130 hours in 53 flight segments, crossed 34 time zones, and flew 15 hours during her home-base sleep hours (10 pm-8 am), incurring 0.13 mGy absorbed dose (0.36 mSv effective dose) of cosmic radiation. About 2% of flight attendant pregnancies were likely exposed to a solar particle event, but doses varied widely. Analyses suggested that cosmic radiation exposure of 0.1 mGy or more may be associated with increased risk of miscarriage in weeks 9-13 (odds ratio = 1.7 [95% confidence interval = 0.95-3.2]). Risk of a first-trimester miscarriage with 15 hours or more of flying during home-base sleep hours was increased (1.5 [1.1-2.2]), as was risk with high physical job demands (2.5 [1.5-4.2]). Miscarriage risk was not increased among flight attendants compared with teachers.
  
  
  CONCLUSIONS
  Miscarriage was associated with flight attendant work during sleep hours and high physical job demands and may be associated with cosmic radiation exposure.
authors.affiliation: From the aNational Institute for Occupational Safety and Health, Cincinnati, OH; and bNational Aeronautics and Space Administration, Hampton, VA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Grajewski
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Whelan
authors.forename: Christina C
authors.initials: CC
authors.lastname: Lawson
authors.forename: Misty J
authors.initials: MJ
authors.lastname: Hein
authors.forename: Martha A
authors.initials: MA
authors.lastname: Waters
authors.forename: Jeri L
authors.initials: JL
authors.lastname: Anderson
authors.forename: Leslie A
authors.initials: LA
authors.lastname: MacDonald
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Mertens
authors.forename: Chih-Yu
authors.initials: CY
authors.lastname: Tseng
authors.forename: Rick T
authors.initials: RT
authors.lastname: Cassinelli
authors.forename: Lian
authors.initials: L
authors.lastname: Luo
mesh_terms: D000022:Abortion, Spontaneous / Q000453:epidemiology / Q000209:etiology*; D000328:Adult; D000337:Aerospace Medicine; D021081:Chronobiology Disorders / Q000150:complications* / Q000453:epidemiology; D003359:Cosmic Radiation / Q000009:adverse effects*; D005178:Faculty; D005260:Female; D006801:Humans; D008875:Middle Aged; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D016017:Odds Ratio; D011247:Pregnancy; D016016:Proportional Hazards Models; D012307:Risk Factors; D057566:Self Report; D014481:United States / Q000453:epidemiology