Table 1

Study eligibility criteria

PICOS domainInclusion criteria
PopulationPregnant women and their unborn children
InterventionsSeasonal and pandemic influenza vaccines of any valency administered during pregnancy that were not contraindicated during pregnancy (eg, live-attenuated vaccines)
ComparatorsNo influenza vaccine, active comparators (eg, other influenza vaccine, meningococcal or pneumococcal vaccines), placebo
OutcomesDichotomous measures of the following:
Maternal

  • Non-obstetric serious adverse events


Birth outcomes:

  • Spontaneous abortion

  • Stillbirth

  • Preterm birth

  • Small-for-gestational-age birth

  • Low birth weight

  • Congenital anomalies

Study designsProspective and retrospective cohort studies, case–control and test-negative studies
Excluded: single-arm cohort studies, studies based on databases of voluntary reporting or surveillance of adverse events, abstracts
LanguageEnglish and French