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- Ludvigsson, Jonas F., 1969-, et al.
(author)
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Maternal Influenza A(H1N1) Immunization During Pregnancy and Risk for Autism Spectrum Disorder in Offspring
- 2020
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In: Annals of Internal Medicine. - : American College of Physicians. - 0003-4819 .- 1539-3704. ; 173:8, s. 597-604
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Journal article (peer-reviewed)abstract
- Background: There are concerns that influenza vaccine exposure during pregnancy may be associated with increased risk for autism spectrum disorder (ASD).Objective: To examine the risk for ASD in offspring of mothers who were vaccinated against influenza A(H1N1)pdm09 ("swine flu") during pregnancy.Design: Population-based cohort study using nationwide registers.Setting: Seven health care regions in Sweden.Participants: Live births between October 2009 and September 2010, with follow-up through December 2016. In total, 39 726 infants were prenatally exposed to H1N1 vaccine (13 845 during the first trimester) and 29 293 infants were unexposed.Measurements: Cox regression was used to estimate hazard ratios (HRs) for the primary outcome, ASD, before and after adjustment for potential confounders. The secondary outcome was autistic disorder (AD).Results: Mean follow up was 6.7 years in both unexposed and exposed children. During follow-up, 394 (1.0%) vaccine-exposed and 330 (1.1%) unexposed children had a diagnosis of ASD. In adjusted analyses, prenatal exposure to H1N1 vaccination was not associated with a later diagnosis of ASD (adjusted HR [aHR], 0.95 [95% CI, 0.81 to 1.12]) or AD (aHR, 0.96 [CI, 0.80 to 1.16]). The 6-year standardized cumulative incidence difference between the unexposed and exposed children was 0.04% (CI, -0.09% to 0.17%) for ASD and 0.02% (CI, -0.09% to 0.14%) for AD. Restricting the analysis to vaccination in the first trimester of pregnancy did not influence risk estimates (aHR, 0.92 [CI, 0.74 to 1.16] for ASD and 0.91 [Cl, 0.70 to 1.18] for AD).Limitation: Data on H1N1 influenza infection are lacking.Conclusion: This large cohort study found no association between maternal H1N1 vaccination during pregnancy and risk for ASD in the offspring. Primary Funding Source: Swedish Research Council.
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| 2. |
- Ludvigsson, Jonas F., 1969-, et al.
(author)
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Risk for Congenital Malformation With H1N1 Influenza Vaccine : A Cohort Study With Sibling Analysis
- 2016
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In: Annals of Internal Medicine. - Philadelphia, USA : American College of Physicians. - 0003-4819 .- 1539-3704. ; 165:12, s. 848-855
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Journal article (peer-reviewed)abstract
- Background: Earlier studies reporting varying risk estimates for congenital malformation in offspring of mothers undergoing vaccination against H1N1 influenza during pregnancy did not consider the potential role of confounding by familial (genetic and shared environmental) factors.Objective: To evaluate an association between maternal H1N1 vaccination during pregnancy and offspring malformation, with familial factors taken into account.Design: Population-based prospective study.Setting: Sweden.Participants: Liveborn offspring born between 1 October 2009 and 1 October 2011 to mothers receiving monovalent AS03-adjuvanted H1N1 influenza vaccine (Pandemrix [GlaxoSmithKline]) during pregnancy. A total of 40 983 offspring were prenatally exposed to the vaccine, 14 385 were exposed within the first trimester (14 weeks), and 7502 were exposed during the first 8 weeks of pregnancy. Exposed offspring were compared with 197 588 unexposed offspring. Corresponding risks in exposed versus unexposed siblings were also estimated.Measurements: Congenital malformation, with subanalyses for congenital heart disease, oral cleft, and limb deficiency.Results: Congenital malformation was observed in 2037 (4.97%) exposed offspring and 9443 (4.78%) unexposed offspring. Adjusted risk for congenital malformation was 4.98% in exposed offspring versus 4.96% in unexposed offspring (risk difference, 0.02% [95% CI, -0.26% to 0.30%]). The corresponding risk differences were 0.16% (CI, -0.23% to 0.56%) for vaccination during the first trimester and 0.10% (CI, -0.41% to 0.62%) for vaccination in the first 8 weeks. Using siblings as comparators yielded no statistically significant risk differences.Limitations: The study was based on live births, and the possibility that data on miscarriage or induced abortion could have influenced the findings cannot be ruled out. Study power was limited in analyses of specific malformations.Conclusion: When intrafamilial factors were taken into consideration, H1N1 vaccination during pregnancy did not seem to be linked to overall congenital malformation in offspring, although risk increases for specific malformations could not be ruled out completely.
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