Intravenous immunoglobulin was licensed for use in the United States in 1981. Currently, there are only a few Food and Drug Administration-labeled indications for intravenous immunoglobulin, but up to 50 "off-label" uses are reported in the literature. The obstetric literature contains numerous reports on intravenous immunoglobulin therapy during pregnancy. This article reviews the properties, pharmacokinetics, mechanisms of action, and side effects of intravenous immunoglobulin, as well as the reported uses of intravenous immunoglobulin during pregnancy.