title: Prenatal influenza exposure and cardiovascular events in adulthood.
abstract: OBJECTIVE
  This study examined the association between prenatal exposure to pandemic influenza and cardiovascular events in adulthood.
  
  
  METHODS
  Using Danish surveillance data to identify months when influenza activity was highest during three previous pandemics (1918, 1957, and 1968), persons were defined as exposed/unexposed based on whether they were in utero during peak months of one of the pandemics. Episodes of acute myocardial infarction (MI) and stroke were identified in the Danish National Registry of Patients covering all Danish hospitals since 1977.
  
  
  METHODS
  Information from Danish national registries on all persons with a Civil Personal Registry number and birthdates in 1915 through 1922, 1954 through 1960, and 1966 through 1972 was collected.
  
  
  METHODS
  Crude incidence rate ratios (IRRs) were calculated per pandemic. Generalized linear models were fit to estimate IRRs adjusted for sex.
  
  
  RESULTS
  For acute MI, sex-adjusted IRRs for persons in utero during peaks of the 1918, 1957, and 1968 pandemics, compared with those born afterward, were 1·02 (95% confidence interval (CI): 0·99, 1·05), 0·96 (95% CI: 0·87, 1·05), and 1·18 (95% CI: 0·96, 1·45), respectively. For stroke, the corresponding IRRs were 0·99 (95% CI: 0·97, 1·02), 0·99 (95% CI: 0·92, 1·05), and 0·85 (95% CI: 0·77, 0·94), respectively.
  
  
  CONCLUSIONS
  There was generally no evidence of an association between prenatal influenza exposure and acute MI or stroke in adulthood. However, survivor bias and left truncation of outcomes for the 1918 pandemic are possible, and the current young ages of persons included in the analyses for the 1957 and 1968 pandemics may warrant later re-evaluation.
authors.affiliation: Massachusetts Department of Public Health, Bureau of Infectious Disease, Jamaica Plain, MA, USA.
authors.forename: Noelle M
authors.initials: NM
authors.lastname: Cocoros
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Lash
authors.forename: Al
authors.initials: A
authors.lastname: Ozonoff
authors.forename: Mette
authors.initials: M
authors.lastname: Nørgaard
authors.forename: Alfred
authors.initials: A
authors.lastname: DeMaria
authors.forename: Viggo
authors.initials: V
authors.lastname: Andreasen
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D007251:Influenza, Human / Q000150:complications*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000453:epidemiology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology*; D020521:Stroke / Q000453:epidemiology*; D055815:Young Adult
keywords: Acute myocardial infarction; influenza; pandemic; stroke