Usually, there is no serious complication for a pregnant woman or her baby because of exposure to a person with Fifth disease. About 50% of women are already immune, and these women and their babies are protected from infection and illness. Sometimes, however, the virus can cause a miscarriage in early pregnancy or severe anemia in the fetus if later in pregnancy. There is no evidence that Fifth disease causes birth defects or mental retardation. If you have been in contact with someone who has Fifth disease, or if you have an illness that might be caused by Parvovirus, please contact us right away so we can determine if blood tests are needed.