title: Birth outcomes for Australian mother-infant pairs who received an influenza vaccine during pregnancy, 2012-2014: The FluMum study.
abstract: In Australia, influenza vaccination is recommended for all women who will be pregnant during the influenza season. Vaccine safety and effectiveness are key concerns and influencers of uptake for both vaccine providers and families. We assessed the safety of receiving an influenza vaccination during any trimester of pregnancy with respect to preterm births and infant birthweight.
  
  
  
  We conducted a nested retrospective cohort study of 'FluMum' participants (2012-2014). Our primary exposure of interest was influenza vaccination during pregnancy. The primary outcomes of interest were infant birthweight and weeks' gestation at birth for live singleton infants. Analyses included comparisons of these birth outcomes by vaccination status and trimester of pregnancy an influenza vaccine was given. We calculated means, proportions, and relative risks and performed multivariable logistic regression for potential confounding factors.
  
  
  
  In the 7126 mother-infant pairs enrolled in this study, mean maternal age at infant birth was 31.7years. Influenza vaccine uptake in pregnancy was 34%. Most mothers with a known date of vaccination received a vaccine in the second trimester (51%). Those mothers with a co-morbidity or risk factor were 13% more likely to have influenza vaccine during pregnancy compared to other mothers (RR 1.13, 95% CI 1.04-1.24, p=0.007). Mean weeks' gestation at birth was 38.7 for the vaccinated and 38.8 for the unvaccinated group (p=0.051). Infants in the vaccinated group weighed 15g less in birthweight compared to the unvaccinated infants (95% CI -12.8 to 42.2, p=0.29).
  
  
  
  Results arising from this large Australian cohort study are reassuring with respect to two critical safety outcomes; preterm births and low infant birthweights. Studies examining a broader range of birth outcomes following influenza vaccination during pregnancy are required, particularly now that maternal vaccination in pregnancy has expanded to include pertussis as well as influenza.
authors.affiliation: National Centre for Epidemiology and Population Health, Research School of Population Health, Australian National University, Canberra, Australian Capital Territory, Australia; The University of Queensland Child Health Research Centre, The University of Queensland, South Brisbane, Queensland, Australia; Menzies School of Health Research, Charles Darwin University, Tiwi, Northern Territory, Australia. Electronic address: lisa.mchugh@menzies.edu.au.
authors.forename: Lisa
authors.initials: L
authors.lastname: McHugh
authors.affiliation: Menzies School of Health Research, Charles Darwin University, Tiwi, Northern Territory, Australia.
authors.forename: Ross M
authors.initials: RM
authors.lastname: Andrews
authors.affiliation: The University of Queensland Child Health Research Centre, The University of Queensland, South Brisbane, Queensland, Australia.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Lambert
authors.affiliation: National Centre for Epidemiology and Population Health, Research School of Population Health, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: Kerri A
authors.initials: KA
authors.lastname: Viney
authors.affiliation: National Centre for Immunisation Research and Surveillance, Sydney Children's Hospitals Network, Discipline of Child and Adolescent Health, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Wood
authors.affiliation: Vaccine and Immunisation Research Group, Murdoch Children's Research Institute and School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Kirsten P
authors.initials: KP
authors.lastname: Perrett
authors.affiliation: Women's and Children's Health Network, Robinson Research Institute and School of Medicine, The University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: Helen S
authors.initials: HS
authors.lastname: Marshall
authors.affiliation: University of Western Australia, School of Paediatrics and Child Health and Vaccine Trials Group, Wesfarmers Centre of Vaccines and Infectious Diseases, Telethon Kids Institute, Perth, Western Australia, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Richmond
authors.affiliation: Institute of Health & Biomedical Innovation, Centre for Children's Health Research, Queensland University of Technology, South Brisbane, Queensland, Australia.
authors.forename: Kerry-Ann F
authors.initials: KF
authors.lastname: O'Grady
mesh_terms: D000328:Adult; D001315:Australia; D001724:Birth Weight / Q000187:drug effects; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects*; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000517:prevention & control*; D011256:Pregnancy Outcome; D047928:Premature Birth / Q000139:chemically induced; D012189:Retrospective Studies
chemical_list: D007252:Influenza Vaccines
keywords: Birth outcomes; Immunisation; Influenza; Maternal vaccination; Pregnancy; Safety