pcb Nordin 2014.

Methods	Retrospective cohort study. Data from 7 Vaccine Safety Datalink sites
Participants	In all, 57,554 women vaccinated and 57,554 matched women not vaccinated during pregnancy introduced in data analysis.
Interventions	Seasonal trivalent inactivated vaccine. Epidemic seasons 2004‐05, 2005‐06, 2006‐07, 2007‐08, 2008‐09 were considered.
Outcomes	Small for gestational age (< 10th or > 5th percentile) Preterm delivery (< 37 weeks or < 34 weeks)
Notes	Founding source ‐ government Data and estimate are pooled for all seasons. This is part of the population of the pcb Nordin 2013 study.
Risk of bias
Bias	Authors' judgement	Support for judgement
PCS/RCS ‐ selection exposed cohort All outcomes	Unclear risk	KP registry
PCS/RCS ‐ selection non‐exposed cohort All outcomes	Unclear risk	KP registry
PCS/RCS ‐ comparability All outcomes	Unclear risk	Matched analysis
PCS/RCS ‐ assessment of outcome All outcomes	Unclear risk	KP registry
Summary assessment	Unclear risk	Unclear risk of bias