ACIP recommends that vaccinated people of childbearing age who have received one or two doses of rubella-containing vaccine and have a rubella serum IgG levels that is not clearly positive should be administered one additional dose of MMR vaccine (maximum of three doses). Repeat serologic testing for evidence of rubella immunity is not recommended. See www.cdc.gov/mmwr/pdf/rr/rr6204.pdf, pages 18–20, for more information on this issue.
MMR vaccines should not be administered to people known to be pregnant or attempting to become pregnant. Because of the theoretical risk to the fetus when the mother receives a live virus vaccine, people capable of bearing children should be counseled to avoid becoming pregnant for 28 days after receipt of MMR vaccine.