Available data on rates of 2009 H1N1 vaccination have not been analysed by sex [91] but rates of seasonal influenza vaccination vary significantly with respect to sex and age [92] [93] [94] . Rates of vaccination among women are lower than men in some European countries [92] and may reflect greater negative beliefs about the risks associated with vaccination [95] , differences in physician recommendations regarding vaccination or occupational differences. Among healthcare workers in China, 73% of women reported intentions to decline both the H5N1 and 2009 H1N1 vaccines compared to 64% of men [96] . In France, acceptance (either receipt or intention to receive) of the 2009 H1N1 vaccine was higher among men and was higher among pregnant women and other groups with co-morbid conditions [97] . In the USA and Canada, vaccination against seasonal and 2009 H1N1 influenza during pregnancy is recommended irrespective of trimester [54, 98, 99] . The vaccination rate of pregnant women against 2009 H1N1 virus has been estimated to be only 38%, which is still higher than that normally seen with seasonal influenza vaccine [91] .