Analysis of pregnancy and infant health outcomes among women in the National Smallpox Vaccine in Pregnancy Registry who received Anthrax Vaccine Adsorbed

Abstract The National Smallpox Vaccine in Pregnancy Registry (NSVIPR) actively follows women inadvertently vaccinated with smallpox vaccine during or shortly before pregnancy to evaluate their reproductive health outcomes. Approximately 65% of NSVIPR participants also inadvertently received Anthrax Vaccine Adsorbed (AVA) while pregnant, providing a ready opportunity to evaluate pregnancy and infant health outcomes among these women. AVA-exposed pregnancies were ascertained using NSVIPR and electronic healthcare data. Rates of pregnancy loss and infant health outcomes, including major birth defects, were compared between AVA-exposed and AVA-unexposed pregnancies. Analyses included AVA-exposed and AVA-unexposed pregnant women who also received smallpox vaccine 28 days prior to or during pregnancy. Rates of adverse outcomes among the AVA-exposed group were similar to or lower than expected when compared with published reference rates and the AVA-unexposed population. The findings provide reassurance of the safety of AVA when inadvertently received by a relatively young and healthy population during pregnancy.