CMV in Pregnancy: Risks and Newborn Manifestations
Congenital CMV infection affects approximately 1 in 200 US newborns and is a leading cause of permanent childhood disability, causing sensorineural hearing loss, intellectual disability, vision loss, and cerebral palsy. 1
Risk of Transmission and Fetal Impact
The risk of vertical transmission and severity of fetal disease depends critically on timing of maternal infection:
- Preconceptional period: 16.7% transmission rate, no symptoms observed in infected newborns 2
- Periconceptional period: 34.5% transmission rate 2
- First trimester: 30.1% transmission rate with highest risk of severe symptoms 2
- Second trimester: 38.2% transmission rate 2
- Third trimester: 72.2% transmission rate but low risk of neonatal disease 2
The greatest risk of severe fetal harm occurs with primary maternal infection around conception and in the first trimester, while infection after 12 weeks appears to carry very low risk. 3, 2
Maternal Infection Characteristics
Up to 50% of maternal CMV infections present with nonspecific symptoms (influenza-like, glandular fever-like, or hepatitis symptoms) or remain completely asymptomatic 4. This makes detection challenging without specific serological testing. Non-primary maternal infections (reactivation or reinfection with different strain) can also cause symptomatic congenital disease, particularly when complicated by gestational hypertensive disorders or gestational diabetes 5.
Clinical Manifestations in Newborns
Symptomatic Disease (10-15% of infected newborns)
Over half of symptomatic newborns will develop long-term disabilities. 1 Clinical signs at birth include:
- Jaundice
- Petechial rash
- Hepatosplenomegaly
- Microcephaly
- Intrauterine growth restriction
- Small brain size
- In severe cases: intrauterine fetal demise 3, 4, 6
Symptomatic infants face hearing loss rates exceeding 40%, with some studies reporting 32.8% developing sensorineural hearing loss 1. Abnormal brain sonographic findings occur in 76.8% of symptomatic cases following primary maternal infection 5.
Asymptomatic Disease (85-90% of infected newborns)
These infants appear completely normal at birth by clinical examination alone, yet up to 20% will develop sensorineural hearing loss in childhood, and emerging research suggests nearly half develop gaze, balance, and vestibular disorders. 1
The hearing loss can be:
- Present at birth but undetected
- Late-onset (appearing months to years later)
- Progressive in nature 1
Prospective data shows hearing loss develops in 2.9% at 6 months and 11.3% at 12 months in asymptomatic infants, demonstrating rapid deterioration 1. Long-term follow-up reveals 25% of asymptomatic cases develop sensorineural hearing loss by 18 years of age 1.
Critical Clinical Pitfalls
Only 57% of infants with cCMV who will develop hearing loss refer on their newborn hearing screen 1, making standard newborn hearing screening insufficient for detection. This is why universal newborn CMV screening is now recommended by major professional societies 1.
All infants with confirmed or suspected maternal CMV infection must be tested within the first 21 days of life using urine or saliva samples 3, as diagnosis after this window cannot distinguish congenital from postnatal infection.
All infants with congenital CMV—regardless of symptoms at birth—require follow-up for at least 2 years to monitor hearing and neurodevelopment 3, as late-onset manifestations are common even in initially asymptomatic cases.
The disease disproportionately affects lower-income and marginalized racial/ethnic groups in the United States, representing a significant health disparities issue 1.