Nausea and vomiting of pregnancy is a common condition that affects the health of the pregnant woman and her fetus. It can diminish the woman's quality of life and also significantly contributes to health care costs and time lost from work (). Because "morning sickness" is common in early pregnancy, the presence of nausea and vomiting of pregnancy may be minimized by obstetricians, other obstetric providers, and pregnant women and, thus, undertreated (). Furthermore, some women do not seek treatment because of concerns about safety of medications (). Once nausea and vomiting of pregnancy progresses, it can become more difficult to control symptoms; treatment in the early stages may prevent more serious complications, including hospitalization (). Mild cases of nausea and vomiting of pregnancy may be resolved with lifestyle and dietary changes, and safe and effective treatments are available for more severe cases. The woman's perception of the severity of her symptoms plays a critical role in the decision of whether, when, and how to treat nausea and vomiting of pregnancy. In addition, nausea and vomiting of pregnancy should be distinguished from nausea and vomiting related to other causes. The purpose of this document is to review the best available evidence about the diagnosis and management of nausea and vomiting of pregnancy.