Management of Cytomegalovirus (CMV) Infection in Pregnancy
Treatment of CMV infection during pregnancy is indicated ONLY for maternal end-organ disease (such as CMV retinitis in HIV-positive patients), NOT for preventing congenital infection in asymptomatic maternal infection. 1
When NOT to Treat
Do not treat asymptomatic maternal CMV infection during pregnancy solely to prevent infant infection. 1 The CDC explicitly states that treatment is not indicated for preventing congenital infection in cases of asymptomatic maternal infection. 1
Do not misinterpret a positive CMV IgG result as evidence of active infection requiring treatment—this only indicates past exposure and immunity, with low risk of congenital CMV. 1, 2
The American College of Obstetricians and Gynecologists recommends that pregnant women with positive CMV IgG alone be considered to have immunity and low risk of congenital CMV. 1, 2
Diagnostic Approach
Maternal Diagnosis
Primary infection: Diagnosed by de-novo appearance of virus-specific IgG in previously seronegative women, or detection of specific IgM antibody associated with low IgG avidity. 3
When to test: Consider serologic testing for women who develop influenza-like illness during pregnancy or following detection of sonographic findings suggestive of CMV infection. 3
Routine screening is NOT recommended for all pregnant women. 3
Fetal Diagnosis
Amniocentesis should be performed at least 7 weeks after presumed maternal infection AND after 21 weeks of gestation to diagnose fetal infection. 3 This timing is critical because it takes 5-7 weeks following fetal infection for detectable virus to be secreted into amniotic fluid. 3
Following primary maternal infection, parents should be informed of a 30-40% risk for intrauterine transmission and 20-25% risk for development of sequelae postnatally if the fetus is infected. 3
Treatment When Indicated (Maternal End-Organ Disease)
First-Line: Valganciclovir
- Valganciclovir is the treatment of choice during pregnancy based on limited data, toxicity reports, and ease of use. 1 However, note that ganciclovir (the active form) is embryotoxic and teratogenic in rabbits. 1
Alternatives (All Have Significant Concerns)
Foscarnet: Associated with increased skeletal anomalies in rats and rabbits; one case report in third trimester showed normal infant outcome. 1
Cidofovir: Do NOT use—embryotoxic and teratogenic in rats and rabbits; not recommended in pregnancy. 1
Monitoring Protocol
When Confirmed or Suspected Fetal Infection
Serial ultrasound examinations every 2-4 weeks until birth to detect sonographic abnormalities. 3 If fetal infection is confirmed, ultrasounds should be performed every 2-3 weeks. 4
Detailed assessment of the fetal brain is essential at each scan. 4
MRI scan of the fetal brain at 28-32 weeks of gestation (sometimes repeated 3-4 weeks later) to assess for brain damage. 4
Key ultrasound findings to monitor: CNS signs (ventriculomegaly, microcephaly), extracerebral signs (hepatosplenomegaly, hyperechogenic bowel, hydrops fetalis indicating substantial anemia). 1, 5
When Maternal Treatment Is Given
Fetal movement counts in the third trimester. 1
Periodic ultrasound monitoring after 20 weeks of gestation to look for hydrops fetalis. 1
Neonatal Testing
All babies born to women with confirmed or suspected CMV infection should be tested with urine or saliva sample within the first 21 days of life. 4
All infants with CMV infection at birth should be followed up at minimum to 2 years of age to check hearing and brain development. 4
Emerging Evidence on Prenatal Antiviral Treatment
While the primary guideline states treatment is not indicated for preventing congenital infection 1, recent research suggests evolving practice:
Valaciclovir (valacyclovir) following primary CMV infection in the first 12 weeks of pregnancy reduces the risk of the baby becoming infected. 4
Valganciclovir for tertiary prevention (treating infected fetuses with ultrasound features) appears well tolerated but requires more extensive trials. 6 A 2024 study showed no neonatal neutropenia and 18% of newborns were asymptomatic at birth. 6
Common Pitfalls to Avoid
Do not treat asymptomatic maternal infection to prevent infant infection. 1
Do not use cidofovir during pregnancy. 1
Do not assume absence of sonographic findings guarantees normal outcome—follow-up is essential. 3
Be aware that false-positive CMV IgM results can occur with Epstein-Barr virus infection or other immune system activation. 2