© 2009 Canadian Medical Association or its licensors

Anew strain of influenza A virus (novel in-fluenza A H1N1) that originated in swine has rapidlyspread from the initial outbreak in Mexico and the southern United States to Canada and many countries in Eu-rope and Asia. Consequently, the World Health Organization raised the level of alert for an influenza pandemic to 5 on Apr. 29, 2009.1 Because many infected people are young,2 the care of pregnant and lactating women is a concern.3–6 According to the US Centers for Disease Control and Pre-vention, the novel H1N1 influenza virus is susceptible to os-eltamivir and zanamivir, neuraminidase-inhibitor antiviral medications, which target the early phase of the infection. However, this strain is resistant to adamantanes, such as amantadine and rimantadine.7 The Centers for Disease Con-trol and Prevention currently recommend antiviral treatment and chemoprophylaxis with either oseltamivir or zanamivir against novel H1N1 influenza for people at high risk of com