Rubella is an infection caused by a virus and is usually mild in children and adults. Congenital rubella syndrome (CRS) is a group of birth defects that occur when the rubella virus infects a fetus. A woman infected with the rubella virus early in pregnancy has a 90% chance of passing the virus on to her fetus and this can lead to death of the fetus or to CRS. The most common birth defect is deafness, but CRS can also cause defects in the eyes, heart and brain.
