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.
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-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.
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.
Tweetable abstract: No increased risk for adverse pregnancy outcomes and infant's health following influenza vaccination.
Keywords: Infant; influenza; pregnancy; safety; vaccination.
© 2015 Royal College of Obstetricians and Gynaecologists.