title: A(H1N1)v2009: a controlled observational prospective cohort study on vaccine safety in pregnancy.
abstract: BACKGROUND
  A(H1N1)v2009 influenza vaccination of pregnant women was a challenge for health care providers, as little safety data were available.
  
  
  METHODS
  We prospectively followed the pregnancies of women who were vaccinated at any time during pregnancy or ≤ 4 weeks prior to conception and compared these outcomes to a control cohort matched by the estimated date of birth. Primary endpoints: rate of spontaneous abortion and major malformations. Secondary endpoints: preeclampsia, gestational age at birth, and birth weight.
  
  
  RESULTS
  Pregnancy outcome of 323 women immunized with adjuvanted or non-adjuvanted A(H1N1)v2009 influenza vaccines from 2009-09-28 to 2010-03-31 were compared to 1329 control subjects. The risk for spontaneous abortions (HR 0.89; 95% CI 0.36-2.19) and the rate of major malformations (all trimesters: OR 0.87; 95% CI 0.38-1.77; preconception and first trimester exposure: OR 0.79; 95% CI 0.13-2.64) did not vary between the two cohorts. Furthermore, there was no increase in preeclampsia, prematurity, and intrauterine growth retardation in the vaccinated cohort.
  
  
  CONCLUSIONS
  The results of our study do not indicate a risk for the pregnant woman and the developing embryo/fetus after H1N1 vaccination. We provide and apply methods novel in observational studies on pregnancy outcome, especially if a single dose exposure is investigated.
authors.affiliation: Institute for Clinical Teratology and Drug Risk Assessment in Pregnancy, Charité - Universitätsmedizin Berlin, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Oppermann
authors.forename: Juliane
authors.initials: J
authors.lastname: Fritzsche
authors.forename: Corinna
authors.initials: C
authors.lastname: Weber-Schoendorfer
authors.forename: Brigitte
authors.initials: B
authors.lastname: Keller-Stanislawski
authors.forename: Arthur
authors.initials: A
authors.lastname: Allignol
authors.forename: Reinhard
authors.initials: R
authors.lastname: Meister
authors.forename: Christof
authors.initials: C
authors.lastname: Schaefer
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007252:Influenza Vaccines / Q000009:adverse effects*; D008875:Middle Aged; D011247:Pregnancy; D011256:Pregnancy Outcome; D011446:Prospective Studies; D012307:Risk Factors; D014611:Vaccination / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines