The purpose of this document is to understand immunization during pregnancy. Immunization saves lives and prevents disease. There are many national resources available to help you fine-tune your vaccination practices. If you have not yet incorporated vaccination into your practices, now would be a great time to start. Immunizations are considered one of the major medical achievements of the 20th century. However, inadequate vaccination remains an important public health problem. This document reflects emerging clinical and scientific advances and current information on the safety of vaccines given during pregnancy. The benefits of immunization to the pregnant woman and her neonate usually outweigh the theoretic risk of adverse effects. The theoretic risks of the vaccination of pregnant women with killed virus vaccines have not been identified. Preconceptional immunization of women to prevent disease in the offspring, when practical, is preferred to vaccination of pregnant women with certain vaccines.