Congenital rubella syndrome (CRS) can occur in a developing fetus of a pregnant woman who has contracted rubella during her first trimester. If infection occurs 0–28 days before conception, the infant has a 43% chance of being affected. If the infection occurs 0–12 weeks after conception, the chance increases to 51%. If the infection occurs 13–26 weeks after conception, the chance is 23% of the infant being affected by the disease. Infants are not generally affected if rubella is contracted during the third trimester, or 26–40 weeks after conception. Problems rarely occur when rubella is contracted by the mother after 20 weeks of gestation and continues to disseminate the virus after birth.
Vaccination of women of childbearing age against rubella can prevent congenital rubella syndrome. Therapeutic abortion is an option if early exposure occurs or CRS is suspected antenatally.