pcb Rubinstein 2013.

Methods	Cohort study
Participants	Women with live‐born or stillborn infants of at least 22 weeks or weighing at least 500 g between September 2010 and May 2011 in 49 hospitals of the Public Health Sector in major Argentinian cities were invited to participate in the study.
Interventions	MF‐59 adjuvanted pandemic H1N1 vaccine (Focetria). Information about exposure status and vaccination were obtained from documentation and official registry: vaccination chart, hospital vaccine registries, or centralised registry from the Ministry of Health if available. The non‐exposed group consisted of non‐vaccinated pregnant women. In total, 7293 vaccinated and 23,195 not vaccinated pregnant women were included.
Outcomes	After participants had signed informed consent form, data from the medical record regarding maternal characteristics, evolution of the index pregnancy and delivery, and status of the newborn were extracted. Participants then completed a brief survey to complement the information. Authors collected data on both mothers and newborns up to day 7 after delivery. For cases discharged before day 7, participants were contacted by telephone at day 7 to check their health status. During the data collection period, a supervisory team visited the participating hospitals weekly to collect and check completion of the forms and to check the quality of the information by reviewing the birth record and clinical record. 2 field supervisors reviewed all forms before information was entered into the database. The following outcomes were considered: Preterm delivery (< 37 weeks): defined as a newborn with a gestational age of less than 37 weeks according to physical examination at birth. Low birth weight (< 2500 g): newborn weighing less than 2500 g. Very low birth weight (< 1500 g): newborn weighing less than 1500 g. Congenital malformations: defined as a newborn presenting with alterations in anatomical development occurring during intrauterine life and diagnosed during gestation or by physical examination within the first 7 days after birth. Early neonatal mortality: defined as death of a newborn within 7 days after birth, foetal mortality as intrauterine death of the foetus in a pregnancy over 22 weeks, and perinatal mortality as early neonatal mortality plus foetal mortality. Low Apgar scores at 5 minutes: defined as a newborn presenting with an Apgar score of less than 7 at 5 minutes. Admission to neonatal intensive care: defined as admission of a newborn to the intensive care unit for a period longer than 48 hours.
Notes	Funding source ‐ industry This study was funded by an independent research grant from Novartis Argentina SA (Internal Protocol No V111_17TP. 2010). The investigators designed and conducted the study; performed the analysis and interpretation of the data; and are responsible for the results, conclusions, and recommendations. Sensitivity analysis was performed by excluding those participants for whom vaccination records were not available.
Risk of bias
Bias	Authors' judgement	Support for judgement
PCS/RCS ‐ selection exposed cohort All outcomes	Low risk	The study was performed in 49 public hospitals where about 113,000 deliveries occur annually (about 15% of overall annual live births in Argentina). This is a somewhat representative sample of newborn populations.
PCS/RCS ‐ selection non‐exposed cohort All outcomes	Low risk	Drawn from the same population as the exposed cohort
PCS/RCS ‐ comparability All outcomes	Low risk	Possible confounding factors have been taken into account.
PCS/RCS ‐ assessment of outcome All outcomes	Low risk	Hospital medical records
Summary assessment	Low risk	Low risk of bias