Pregnant women are at increased risk of serious adverse effects from influenza. As a result, government agencies in the United States and Europe recommend neuraminidase inhibitors for the treatment of parturients with influenza as well as prophylaxis in pregnant women exposed to the virus. However, the safety of these drugs for the fetus has not been well established. As a result of the 2009 H1N1 pandemic there was a large increase in the number of pregnant women exposed to neuraminidase inhibitors. While previous observational studies have not found any connection between neuraminidase inhibitor use during pregnancy and adverse fetal or neonatal outcomes, including congenital anomalies, no randomized controlled study in parturients has been performed. This study looked at the risks of adverse birth outcomes associated with in utero exposure to 2 neuraminidase inhibitors: oseltamivir and zanamivir.