Table 1.

Study eligibility criteria

PICOS domain	Inclusion criteria
Population	Pregnant women and their unborn children
Interventions	Seasonal and pandemic influenza vaccines of any valency administered during pregnancy that were not contraindicated during pregnancy (eg, live-attenuated vaccines)
Comparators	No influenza vaccine, active comparators (eg, other influenza vaccine, meningococcal or pneumococcal vaccines), placebo
Outcomes	Dichotomous 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 designs	Prospective 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
Language	English and French