The recommendation for seasonal flu immunization from the second trimester of pregnancy, adopted in summer 2010 in Switzerland, is situated within a social context characterized by reluctance toward some vaccinations, a relatively low vaccination coverage against flu in the general population, and still heated debates fuelled by vaccination campaigns organized around the A(H1N1)pdm09 flu pandemic in winter 2009 to 2010. This study examines Swiss pregnant women's representations of the risks associated with seasonal flu and its vaccination.