What are the preventive measures and treatment options for CMV (Cytomegalovirus) infection in pregnancy and its effects on the fetus?

CMV Infection in Pregnancy: Prevention and Management

Primary Prevention Through Hygiene Measures

The most effective current strategy for preventing CMV infection in pregnancy is hygiene education, particularly for women in regular contact with young children, as transmission commonly occurs through exposure to infected saliva and urine. 1, 2, 3

Key Preventive Behaviors

• Thorough handwashing after contact with young children's bodily fluids (saliva, urine, diapers) is essential 4
• Avoid sharing utensils, food, or drinks with young children 5
• Avoid kissing young children on the mouth 5
• Use latex condoms during sexual contact to reduce transmission risk 4
• For CMV-seronegative pregnant women requiring blood transfusion, use only CMV antibody-negative or leukocyte-reduced cellular blood products 4

Common Pitfall: Despite recommendations from CDC and ACOG, fewer than 44% of obstetricians counsel patients about CMV prevention, representing a major gap in prenatal care 6. All pregnant women, especially those with regular contact with young children (including childcare providers), should receive this counseling 4.

Screening and Diagnosis

Current Screening Recommendations

• Universal antenatal or newborn screening for CMV is NOT recommended 1
• Testing should be offered to pregnant women with:
  • Influenza-like symptoms, glandular fever, or hepatitis during pregnancy 1
  • Fetal anomalies on ultrasound suggesting possible CMV infection 1
  • Women at high risk who belong to groups with low CMV seropositivity rates 4

Diagnostic Approach

• Primary maternal CMV diagnosis requires either:
  • Seroconversion (de novo IgG appearance in previously seronegative women) 3
  • Detection of specific IgM and IgG antibodies with low IgG avidity 3
• Prenatal fetal diagnosis via amniocentesis should be performed at least 8 weeks after presumed maternal infection and after 17 weeks of gestation 3

Antiviral Treatment During Pregnancy

Maternal Treatment for Primary Infection

Following primary CMV infection in the first 12 weeks of pregnancy, valaciclovir (valacyclovir) reduces the risk of vertical transmission to the fetus. 1

• This represents the most significant recent advance in preventing congenital CMV infection
• Treatment should be initiated as soon as primary infection is confirmed in early pregnancy 1

Important Caveats

• No antiviral prophylaxis is routinely recommended for pregnant women to prevent CMV acquisition 4
• Oral ganciclovir prophylaxis is only considered for HIV-infected individuals with CD4+ counts <50 cells/µL, not for general pregnancy prevention 4
• Acyclovir and valacyclovir are NOT effective for CMV disease prevention 4

Fetal Monitoring After Maternal Infection

When Fetal Infection is Confirmed

• Ultrasound scans every 2-3 weeks until birth 1
• Detailed fetal brain assessment is essential 1
• MRI scan of fetal brain at 28-32 weeks gestation (sometimes repeated 3-4 weeks later) 1

When Maternal Infection Occurs Without Confirmed Fetal Infection

• Repeated ultrasound scans every 2-3 weeks until birth 1

Neonatal Diagnosis and Treatment

Immediate Postnatal 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. 1

Neonatal Treatment Indications

For symptomatic congenital CMV infection at birth, treatment with valganciclovir or ganciclovir initiated in the first month of life:

• Reduces hearing loss in 5 out of 6 babies 1
• Improves long-term neurodevelopmental outcomes 1, 5

Critical Timing: Antiviral treatment must be initiated within the first month of life for symptomatic infants to achieve these benefits 5.

Long-term Follow-up

• All infants with CMV infection at birth require follow-up for at least 2 years to monitor hearing and brain development 1
• This applies even to asymptomatic infants, as 15-25% will develop long-term adverse neurodevelopmental conditions despite appearing normal at birth 2

Risk Stratification by Timing of Infection

Highest Risk Period

The greatest risk of fetal harm occurs with primary maternal CMV infection before 12 weeks of pregnancy 1

• Transmission rates after primary infection: up to 50% 5
• Risk appears very low following infection after 12 weeks 1

Non-Primary Infection

• Transmission rates with reactivation or reinfection: <2% 5
• Past infection does NOT confer complete immunity or fully protect the fetus 3

Special Considerations for HIV-Infected Pregnant Women

• CMV prevalence is approximately 90% in HIV-infected pregnant women (higher than general population) 4
• CMV shedding from cervix is higher: 52-59% vs 14-35% in HIV-uninfected women 4
• Risk of mother-to-child CMV transmission may be increased: 4.5% vs <2% in general population 4
• Good hygiene practices remain the primary prevention strategy 4

Key Clinical Outcomes

Congenital CMV Burden

• Affects 1 in 200 live births in high-income countries; 1 in 71 in low- and middle-income countries 1
• Leading cause of non-genetic sensorineural hearing loss 1, 2
• Major cause of cognitive impairment and cerebral palsy 1, 3
• Approximately 1 in 8 babies with congenital CMV have clinically detectable signs at birth 1

Maternal Presentation

• Most maternal CMV infections are asymptomatic or present with mild cold-like symptoms 2, 5
• May manifest as mononucleosis-like syndrome with persistent fever and fatigue 5