If a woman has rubella during pregnancy, the rubella virus can induce many different birth defects (known as 'Rubella Syndrome' or 'Congenital Rubella'), some of which are quite severe.
Among the defects doctors have seen in congenital rubella are eye defects (cataracts, glaucoma, "microphthalmia" [small, non-functional eyes]), heart problems (defects of the wall between the two sides of the heart, narrowing of the arteries to the lungs, and an open duct bypassing the lungs), ear problems (deafness caused by defects in the nerves and sound-sensing organs), and neurologic problems (including mental retardation) — among others.