RT Journal Article SR Electronic T1 Association between maternal influenza vaccination and neurodevelopmental disorders in childhood: a longitudinal, population-based linked cohort study JF Archives of Disease in Childhood JO Arch Dis Child FD BMJ Publishing Group Ltd and Royal College of Paediatrics and Child Health SP 647 OP 653 DO 10.1136/archdischild-2022-324269 VO 108 IS 8 A1 Foo, Damien A1 Sarna, Mohinder A1 Pereira, Gavin A1 Moore, Hannah C A1 Regan, Annette K YR 2023 UL http://adc.bmj.com/content/108/8/647.abstract AB Objective To assess the association between in utero exposure to seasonal inactivated influenza vaccine (IIV) and the risk of a diagnosis of a neurodevelopmental disorder in early childhood.Design Retrospective cohort study.Setting Population-based birth registry linked with health administrative databases in Western Australia (WA).Participants Singleton, liveborn children born between 1 April 2012 and 1 July 2016 in WA.Exposure Receipt of seasonal IIV during pregnancy obtained from a state-wide antenatal vaccination database.Main outcome measures Clinical diagnosis of a neurodevelopmental disorder was recorded from hospital inpatient and emergency department records. We used Cox proportional hazard regression, weighted by the inverse-probability of treatment (vaccination), to estimate the hazard ratio (HR) of neurodevelopmental disorders associated with in utero exposure to seasonal IIV.Results The study included 140 514 children of whom, 15 663 (11.2%) were exposed to seasonal IIV in utero. The prevalence of neurodevelopmental disorders was 5.4%, including mental or behavioural (0.4%), neurological (5.1%), seizure (2.2%) and sleep disorders (2.7%). Maternal IIV was not associated with increased risk of neurodevelopmental disorders (HR 1.00; 95% CI 0.91 to 1.08). Children exposed in the first trimester had a lower risk of seizure disorders (adjusted HR [aHR] 0.73; 95% CI 0.54 to 0.998), and preterm children exposed any time during pregnancy had a lower risk of sleep disorders (aHR 0.63; 95% CI 0.41 to 0.98).Conclusions We did not observe increased risk of neurodevelopmental disorders following in utero exposure to seasonal IIV. Although we observed some evidence for lower risk of seizure and sleep disorders, additional studies are required to confirm.No data are available. This study is part of a larger linked cohort study and was guided by the study protocol described elsewhere. The linked administrative data are de-identified and are not owned by the authors. Access to the data is approved by the Data Custodians and provided by the WA Data Linkage Branch within the WA Department of Health (https://www.datalinkage-wa.org.au/contact-us/). The use of the data is restricted to named researchers only.