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 â ), measured by pregnancy outcomes and infant's health.Design Cross-sectional linkage study.Setting and sample 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.Main outcome measures Multivariate logistic regression was used to assess the association between H1N1 vaccination and small-forgestational-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 infectionrelated 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 (À0.05; 95% CI À0.13 to 0.04), length-for-age (À0.01; 95% CI À0.09 to 0.06), head-circumference-for-age (À0.05; 95% CI À0.13 to 0.03), developmental scores (À0.06; 95% CI À0.28 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.Conclusion 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.Keywords Infant, influenza, pregnancy, safety, vaccination.Tweetable abstract No increased risk for adverse pregnancy outcomes and infant's health following influenza vaccination.Please cite this paper as: van der Maas N, Dijs-Elsinga J, Kemmeren J, van Lier A, Knol M, de Melker H. Safety of vaccination against influenza A (H1N1) during pregnancy in the Netherlands: results on pregnancy outcomes and infant's health: cross-sectional linkage study. BJOG 2016;123:709-717.
IntroductionIn spring 2009 an influenza A (H1N1) pandemic occurred. Influenza during pregnancy increases the risk of hospitalisation due to respiratory complications, especially for women with co-morbidity.1-3 Furthermore, during the 2009 pandemic, an increased risk of adverse pregnancy outcomes after infection was reported.4-6 Therefore, the Dutch Health Council advised all pregnant wo...