To determine if you have sufficient rubella antibodies to protect you from the rubella virus; to verify a past infection or detect a recent infection. Rubella is an illness with flu-like symptoms followed by a rash. Common symptoms include: low-grade fever, headache, runny nose, red eyes, and muscle or joint pain. It is usually a mild virus. It is very dangerous for a pregnant woman to have this virus during the first 20 weeks of her pregnancy. She could lose the baby or casue some serious complications such as cataracts, deafness, or damage to the heart or brain.