What Is Congenital Cytomegalovirus?

Congenital cytomegalovirus (CMV) is a condition found in newborns who were infected with this virus while in the womb. The greatest risk for developing this condition occurs when a mother who had not been previously exposed to this virus is infected early in the course of her pregnancy. Although many infants are asymptomatic after in utero exposure to CMV, some have severe manifestations, including low blood counts and a malformed brain. Treatment of congenital cytomegalovirus infection focuses on treating the symptoms and using intravenous antiviral medications.

The human cytomegalovirus is a pathogenic agent that infects many people worldwide. It is commonly transmitted via contact with bodily fluids, including saliva and urine. Once the virus enters the body, it invades cells and replicates inside of them. The virus can often remain dormant in the human body for years after infection.

Problems can arise when a pregnant woman is infected with CMV for the first time. The virus infects the mother, replicates within her cells, and sends new viral particles into the maternal bloodstream. These copies of CMV can cross through the placenta and enter the fetal circulation, causing infection in the developing baby. The fetus typically has the worst infection if exposed to CMV early in the developmental process, especially within the first trimester of the pregnancy.

Manifestations of congenital cytomegalovirus infection can vary, with some infants being asymptomatic and others having severe symptoms. As many as 90% of infants who had evidence of exposure to CMV prior to birth were initially asymptomatic and had no major problems. Some of these babies, however, went on to have problems with learning disabilities, mental retardation, and hearing loss. These late-developing symptoms are often never associated with CMV due to their delayed presentation.

Other infants exposed to CMV in utero are born with severe symptoms of congenital cytomegalovirus. They can have a low birth weight, low red blood cell counts, jaundice, decreased counts of platelets in their blood, and enlarged livers. Some also have birth defects that alter their physical appearance, including microcephaly, or having a small head. These babies with severe findings often have poor prognoses and have problems with mental retardation, seizures, and motor development.

Treatment of congenital cytomegalovirus infection typically focuses on alleviating the symptoms caused by the disease. For example, a baby born with a low red blood cell count might be treated with a blood transfusion. Some researchers have investigated the benefits of treating affected infants with intravenous antiviral medications and have found that this therapy could help decrease the progression of some symptoms. For mothers who had an infection with CMV early in their pregnancies that caused severe congenital deformities obvious on prenatal ultrasound, elective termination is sometimes offered. Treatment with antiviral agents during the course of the pregnancy has not been shown to offer any benefits.