Cytomegalovirus, otherwise known as CMV, is the most common congenital infection in the United States, affecting about 1 percent of all newborns. Still, few people have heard of CMV, a viral infection from one of the herpes family of viruses.

Most women of reproductive age—up to 80 percent—are exposed to CMV at some time in their lives and are unlikely to be at risk during pregnancy. On the other hand, a pregnant woman newly infected with CMV has a 40 percent chance of passing the virus to her fetus. It can cause a fetal infection that leads to serious illness or disabilities.

CMV passes through contact with infected body fluids—saliva, urine, blood and mucus—or sexual contact. Infected adults may develop mild symptoms such as sore throat, fever and body aches. Less commonly, CMV can cause pneumonia or serious eye-infections, especially in individuals with compromised immune systems.

Although the vast majority of babies infected with CMV have no symptoms from this virus, about 10 percent of infected babies will develop neurological abnormalities such as mental retardation, learning disabilities, hearing loss or visual impairment. Sadly, congenital CMV is the most common cause of hearing loss in children.

Some 10 to 15 percent of infected newborns have symptoms at birth, including jaundice (yellow skin), a rash or an enlarged spleen or liver. Symptomatic infants have an increased risk of death, and those who survive may have neurological problems.

There is no accepted treatment to prevent passage of the virus from an infected mother to her baby, nor is there treatment to prevent infected newborns from developing complications of CMV. Some physicians may use an anti-viral drug called gancyclovir for life-threatening or sight-threatening maternal infections. Also, research is being done to see if a vaccine might protect women of childbearing age from becoming infected.

The best way to reduce the risk of CMV is to practice good hygiene before and during pregnancy. This is especially important for women in contact with young children, including childcare providers and healthcare workers. Up to 70 percent of young children shed the CMV virus and can pass it to family members and caretakers. To prevent the spread of this virus:

• Wash your hands thoroughly after any contact with saliva and urine of young children. This includes washing after picking up toys used by children.
• Carefully dispose of diapers and tissues and wash your hands thoroughly after changing diapers.
• Don't share utensils or drinking glasses with young children.
• Don't share food with young children.

In my practice, medical and childcare workers are offered a blood test prior to conception to see if they have immunity to CMV. Women with evidence of past exposure to CMV are not at high risk of developing such an infection during pregnancy. Women who do become infected during pregnancy can have an amniocentesis done to determine if the infection has spread.