title: Safety of vaccination against influenza A (H1N1) during pregnancy in the Netherlands: results on pregnancy outcomes and infant's health: cross-sectional linkage study.
abstract: OBJECTIVE
  This study aims to assess the safety of Influenza A(H1N1), vaccination administered during the second and third trimester and containing MF59 and thiomersal (Focetria(®) ), measured by pregnancy outcomes and infant's health.
  
  
  METHODS
  Cross-sectional linkage study.
  
  
  METHODS
  A sample of pregnant women, eligible for prenatal screening, were invited to participate.
  
  
  METHODS
  Questionnaire data were linked with the Netherlands Perinatal Registry (n = 1920). Information on infant growth, development (n = 1739) and infection-related contacts with the general practitioner (GP) during the first year of life (n = 1671) was obtained.
  
  
  METHODS
  Multivariate logistic regression was used to assess the association between H1N1 vaccination and small-for-gestational-age infant, preterm delivery and a composite adverse outcome, i.e. low Apgar-score, neonatal intensive care unit admission, neonatal resuscitation or perinatal death. Influence of maternal vaccination on growth, development and GP infection-related contact rates were assessed using multivariate linear mixed modelling and multivariate negative binomial regression, respectively.
  
  
  RESULTS
  Response rate was 21%. Though we found differences in characteristics between unvaccinated and vaccinated women, in the multivariate analyses no association was found between H1N1 vaccination and small-for-gestational-age (odds ratio [OR] 0.84; 95% confidence interval [95% CI] 0.50-1.43), preterm delivery (OR 0.98; 95% CI 0.59-1.62) and the composite adverse outcome (OR 0.84; 95% CI 0.44-1.60). We found no differences in weight-for-age (-0.05; 95% CI -0.13 to 0.04), length-for-age (-0.01; 95% CI -0.09 to 0.06), head-circumference-for-age (-0.05; 95% CI -0.13 to 0.03), developmental scores (-0.06; 95% CI -0.28 to 0.17) and infection-related GP contact rates (incidence rate ratio 1.07; 95% CI 0.91-1.28) between infants of unvaccinated and vaccinated mothers.
  
  
  CONCLUSIONS
  Pregnancy outcomes did not differ between H1N1-vaccinated and unvaccinated women. Furthermore, growth, development and GP infection-related contact rates, assessed after the first year of life, were similar in offspring of vaccinated and unvaccinated mothers.
  
  
  CONCLUSIONS
  No increased risk for adverse pregnancy outcomes and infant's health following influenza vaccination.
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.
authors.forename: N
authors.initials: N
authors.lastname: van der Maas
authors.affiliation: The Netherlands Perinatal Registry, Utrecht, the Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Dijs-Elsinga
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Kemmeren
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: van Lier
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Knol
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: de Melker
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006306:Health Surveys; D006801:Humans; D007223:Infant; D000068104:Infant Health; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects*; D007251:Influenza, Human / Q000517:prevention & control*; D016247:Information Storage and Retrieval; D016014:Linear Models; D016015:Logistic Models; D015999:Multivariate Analysis; D009426:Netherlands; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000517:prevention & control*; D011256:Pregnancy Outcome; D016896:Treatment Outcome
chemical_list: D007252:Influenza Vaccines; C558220:focetria
keywords: Infant; influenza; pregnancy; safety; vaccination