CMV in Pregnancy: Effects on the Developing Embryo and Fetus, Diagnosis and Treatment. Where to Go Now?

Cytomegalovirus (CMV) is the most teratogenic human virus often manifested with atypical clinical findings. Fetal damage is highest following primary maternal infection during the first trimester of pregnancy with transfer increasing with pregnancy advancement. CMV damage may continue to intensify during the early postnatal years. Viral load enables prediction of fetal infection; its reduction by maternal treatment with valacyclovir may reduce the rate and severity of fetal infection. Definite fetal infection may be diagnosed by amniocentesis and viral DNA detection and brain involvement by ultrasound or MRI. The most common fetal damage is hearing loss alongside a variety of brain lesions resulting in significant neurological deficits, including intellectual impairment. The clinical manifestations are either evident at birth (cCMV) or gradually appear postnatally. Pharmacological treatment with ganciclovir or valganciclovir, if initiated early after birth, reduces hearing loss progress and possibly ameliorates other neurological deficits. As of today, there is no approved CMV vaccine for prevention. The mRNA-1647’s vaccine, that is in phase 3 clinical trial, seems to be promising. The IgG avidity testing improved the ability to define recent from old infection and, indirectly, primary from non-primary infection. These advances should make us raise the need of screening pregnant women in the first trimester and newborn infants of mothers suspected of having primary CMV infection. Alternatively, at least infants who fail the screening hearing test. Such recommendations were made recently by a group of experts in Europe. Infants with clinical manifestations should be offered treatment as early as possible following diagnosis.