We propose to follow a cohort of pregnant and post-partum Canadian women through the fall and
winter of 2009/2010 and the anticipated second and third waves of the current pandemic in
order to better understand the incidence, complications and risk factors for severe disease
due to H1N1 influenza in pregnant women, and to contribute data on the safety and
effectiveness of antivirals and vaccines in this population.
The primary hypotheses to be tested are:
(i) pandemic influenza infection in the second and third trimester of pregnancy is associated
with an increase in adverse fetal outcomes (fetal loss, stillbirth, neonatal mortality,
significant neonatal morbidity, prematurity) (ii) close contact with young children (<2 yrs)
at home or work is the most important risk factor for influenza in pregnant women (iii)
higher scores on a scale of community infection prevention (a combination of self-reported
hand hygiene adherence, avoidance of ill persons and avoidance of crowds) are protective
against influenza (iv) receipt of seasonal influenza vaccine from 2007 to 2009 will increase
the risk of illness due to influenza A(H1N1)v in the second and third waves of the pandemic.
(v) pandemic influenza vaccine is effective in preventing symptomatic influenza in pregnant
(vi) vaccination of pregnant women against a particular strain of influenza protects their
infants against influenza infection in the first six months of life.