I recently learned that June is CMV awareness month. Let's take a moment to review CMV....

What is CMV? 🩺

Cytomegalovirus (CMV) is a very common type of virus. CMV is part of the herpes family and affects 1 in 200 infants at birth, with 1 in 5 having birth defects. According to the CDC, over half of adults are infected by CMV by the time they are 40.

CMV is found in body fluids, like saliva, blood, breast milk, seminal and vaginal fluids. Mother's who experience a primary infection (first time they're ever infected) early in pregnancy have infants who experience that most sequelae.

Learn More from the CMV Foundation

Pathophysiology

Cytomegalovirus (CMV) causes injury to the fetus through a combination of viral activity, the mother's immune response, and placental changes. The damage often results from the virus actively replicating and destroying cells, as well as inflammation from the body's attempt to fight the infection.

Several factors influence how severe CMV-related injury can be:

• Timing of Infection: Infection earlier in pregnancy poses a higher risk.

• Maternal Immune Status: A mother's immune defenses can impact fetal outcomes.

• Placental Health: Placental damage can lead to growth restriction and poor oxygen delivery.

• Viral Load: Higher amounts of virus in the amniotic fluid are linked to worse outcomes.

• Strain Differences: Some CMV strains may be more harmful than others.

• Fetal Immune and Genetic Response: How the fetus responds at a cellular level also plays a role.

The placenta is central to fetal injury, with CMV infection causing inflammation, disrupting normal placental function, and contributing to intrauterine growth restriction (IUGR).

The fetal brain is especially vulnerable, with CMV affecting brain development by:

• Disrupting neural migration

• Increasing neural cell death

• Altering normal brain structure and immune function

Other organ systems can be affected, including:

• Ears (leading to sensorineural hearing loss from inflammation of inner ear structures)

• Eyes

• Liver

• Lungs

• Kidneys

• Endocrine glands

CMV-infected cells have been found in critical structures like the cochlea, semicircular canals, and vestibular system, explaining the high risk for hearing loss and balance issues in affected infants.

Clinical Presentation

Only about 10-15% of babies with congenital CMV show symptoms at birth, but when they do, it can affect nearly any organ system ranging from mild illness to severe, life-threatening disease.

Common Signs in Symptomatic Newborns Include:

• Growth concerns: Prematurity and small for gestational age

• Visible symptoms:

  • Jaundice

  • Hepatosplenomegaly (enlarged liver and spleen)

  • Lethargy

  • Respiratory distress

  • Seizures

  • Petechial rash (the classic "blueberry muffin" rash)

    • This is a common RNC-NIC question

• Lab findings:

  • Thrombocytopenia (low platelets)

  • Anemia

  • Elevated liver enzymes and conjugated bilirubin

Central Nervous System (CNS) Involvement is Common
Babies may present with:

• Hypotonia (low muscle tone)

• Lethargy

• Seizures

• Microcephaly

  • Recall the pathophysiology, CMV infection disrupts neuronal migration which results in Microcephaly

Brain imaging may reveal:

• Intracranial calcifications

• Periventricular cysts

• Ventriculomegaly (enlarged ventricles)

• Cerebellar hypoplasia

• White matter changes

Other Key Complications to Watch For:

• Eye disease in 20-40% of symptomatic infants

  • Retinal scars

  • Optic atrophy

  • Chorioretinitis

• Sensorineural Hearing Loss (SNHL):

  • Affects 40-70% of symptomatic infants

  • Can also affect 10-15% of infants with no other symptoms

  • May be present at birth or develop later, even into childhood

  • Hearing loss can range from mild, unilateral to profound, bilateral deafness

  • SNHL may fluctuate or progressively worsen over time

Outcomes:

• Neonatal mortality is rare (likely <5%)

• However, 50-75% of symptomatic infants have long-term neurodevelopmental challenges, such as:

  • Motor impairments or cerebral palsy

  • Seizures

  • Vision and hearing loss

  • Intellectual or learning disabilities

Good news: Most infants with asymptomatic congenital CMV have normal intellectual development, though hearing should still be closely monitored over time.

Video on CMV from Osmosis

How is CMV Diagnosed?

Prenatal Diagnosis

• Routine CMV screening is not standard during pregnancy, but testing can be done if CMV infection is suspected.

• Recommended tests include:

  • CMV IgG and IgM antibodies

  • IgG avidity testing to help determine if infection is recent (low avidity = recent primary infection).

• Ultrasound clues that may suggest CMV infection:

  • Echogenic bowel

  • Intrauterine Growth Restriction (IUGR)

  • Brain findings: microcephaly, ventriculomegaly, periventricular calcifications

  • Polyhydramnios, fetal hydrops, hepatosplenomegaly, placental enlargement

• Abnormal ultrasound findings increase the risk of long-term complications, while normal cranial imaging is reassuring.

• Amniotic Fluid PCR Testing:

  • Recommended after 20 weeks' gestation and at least 6 weeks post maternal infection

  • Detects fetal CMV by identifying viral DNA in the amniotic fluid

Postnatal Diagnosis

• Best confirmed by detecting CMV in urine or saliva samples collected within the first 2–3 weeks of life.

• After 3 weeks, positive results may reflect postnatal CMV infection.

• Preferred testing method: CMV PCR, which is more sensitive than older culture methods.

Recommended Evaluation for Diagnosed Infants

All infants with confirmed congenital CMV should receive:
✔️ Complete blood count
✔️ Liver function tests
✔️ Hearing evaluation
✔️ Eye exam (especially for symptomatic infants)
✔️ Cranial imaging (ultrasound and/or MRI)
✔️ Blood CMV PCR to assess viral load

Why it matters:

• CNS disease or abnormal brain imaging predicts higher risk for long-term disabilities.

• Eye exams are critical for symptomatic infants; asymptomatic infants with normal exams rarely develop later vision issues.

• Even infants who pass their newborn hearing screen need ongoing monitoring for delayed or progressive hearing loss.

• All infected infants should receive developmental follow-up and early intervention if delays arise.

Future Pregnancies

• Mothers with low CMV IgG avidity (recent infection) may need counseling before future pregnancies. Some experts suggest delaying conception until high-avidity antibodies develop, indicating immunity.

Treatment for Symptomatic Infants

• Ganciclovir and Valganciclovir, antiviral medications, have been shown to:

  • Improve hearing outcomes

  • Reduce developmental delays

• Studies show:

  • 6 weeks of IV Ganciclovir improves hearing at 6 months and reduces developmental concerns at 6 and 12 months.

  • 6 months of oral Valganciclovir improves hearing and neurodevelopmental outcomes at 12 and 24 months.

Who should receive treatment?

• All symptomatic infants with any CNS involvement, including:

  • Microcephaly

  • Abnormal brain imaging

  • Positive CMV DNA in cerebrospinal fluid

  • Chorioretinitis

  • Sensorineural hearing loss (SNHL)

• Infants with severe or life-threatening end-organ CMV disease, even if postnatally acquired

Monitoring during treatment:

• Neutropenia is a known side effect, requiring careful blood count monitoring.

• Infants with CMV chorioretinitis need coordinated care with an ophthalmologist and infectious disease specialist.

What about asymptomatic babies or older infants?

• Current evidence does not support antiviral treatment for:

  • Asymptomatic infants

  • Older infants with isolated hearing loss

Prevention: The Most Powerful Tool

Since many maternal CMV infections are silent, prevention focuses on education and hygiene:

Key Prevention Tips for Women of Childbearing Age:
✔️ Wash hands after contact with young children’s saliva or urine
✔️ Avoid sharing food, drinks, utensils, or toothbrushes
✔️ Avoid kissing children on the mouth or cheek

Why it matters:

• Young children are a major source of CMV for pregnant women.

• Surveys show only 14–30% of women have even heard of CMV, highlighting the need for public education.

Prenatal CMV Screening:

• Not routinely recommended due to:

  • Risk of false reassurance from a positive CMV IgG (immunity) result

  • Possibility of reinfection with a different CMV strain

Future Outlook

• No approved CMV vaccines yet, but several are in clinical trials.

• An effective vaccine could be a game-changer for preventing congenital CMV in the future.

What NICU Nurses Need to Know About Congenital CMV

CMV is the most common congenital infection and a leading cause of hearing loss and neurodevelopmental delays in infants. As NICU nurses, we play a critical role in early identification, supportive care, and family education.

✔️ Not all babies show symptoms at birth

• Only 10–15% of CMV-infected infants are symptomatic

• Symptomatic babies may present with:
  ▪️ Petechial rash
  ▪️ Jaundice
  ▪️ Hepatosplenomegaly
  ▪️ Microcephaly
  ▪️ Respiratory distress
  ▪️ Seizures

✔️ Look out for CNS involvement

• Microcephaly, abnormal cranial imaging, hypotonia, seizures, or lethargy may signal CMV affecting the brain

• Intracranial calcifications or ventriculomegaly on imaging raise suspicion

✔️ CMV is confirmed by testing urine or saliva within the first 3 weeks of life

• PCR is the most reliable test

• After 3 weeks, positive results may reflect postnatal, non-congenital infection

✔️ Symptomatic infants with CNS involvement qualify for antiviral therapy

• Treatment with valganciclovir for 6 months can improve hearing and developmental outcomes

• Nurses should monitor for side effects, especially neutropenia

✔️ All infected infants need follow-up

• Even asymptomatic infants can develop progressive hearing loss

• Ongoing hearing screens, developmental assessments, and early intervention referrals are essential

✔️ Prevention starts with education

• Counsel families about CMV prevention—good hand hygiene, avoiding saliva exposure from young children, and not sharing food or drinks

Bottom line: Early detection, appropriate management, and family education can make a difference in outcomes for infants with congenital CMV.

You Make the Difference

Caring for infants with congenital CMV can feel overwhelming—but your knowledge and compassionate care change lives. Early detection starts with the NICU team noticing the subtle signs, advocating for testing, and guiding families through the next steps.

Every time you help a family understand their baby’s diagnosis…
Every time you catch those small details that lead to early treatment…
Every time you teach prevention to a parent or caregiver…

You’re making an impact that lasts a lifetime. 💛

Keep leading with knowledge. Keep advocating for your tiny patients. You’re the difference in their story.

Amanda

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References:

American Academy of Pediatrics (2025). Congenital Cytomegalovirus. Retrieved https://www.aap.org/en/patient-care/congenital-cytomegalovirus-ccmv/?srsltid=AfmBOooXbDE0GPEp1IyggPloZ5a8ZeZEi1hQrvmKikubaRAuPS210Zwg

Center for Disease Control and Prevention. (2025). About Cytomegalovirus. Retrieved from https://www.cdc.gov/cytomegalovirus/about/index.html

Stokes, C & Melvin, A. (2024) Viral Infections of the Fetus and Newborn in Avery's Diseases of the Newborn (11th Ed.) Elsevier