A common virus that affects 50-70% of adults. If a woman acquires cytomegalovirus (CMV) infection during pregnancy, there is about a 15% chance that her infant will have infection and serious complications. Women who have had CMV infection and who are considering breastfeeding their prematurely born infant should check first with their child's doctor since there is a risk of transmitting the virus to the infant through breast milk. Prematurely born infants may not be able to fight off the CMV infection as do infants born at term. CMV infection is usually a mild infection in adults. Infants born to women who have had CMV long before they became pregnant are at low risk of having an infant with serious CMV infection.