Risk of cytomegalovirus-associated sequelae in relation to time of infection and findings on prenatal imaging

Objective: To determine the outcome of pregnancies with documented fetal cytomegalovirus (CMV) infection with and without abnormal findings on ultrasound examination and magnetic resonance imaging (MRI).

Methods: In this prospective cohort study of pregnant women with documented fetal CMV infection, vertical CMV transmission occurred during the first and second trimesters following primary maternal infection. Patients underwent serial prenatal ultrasound scans and fetal MRI. All neonates underwent ocular fundus examination, ultrasound brain scan and hearing evaluation, and were then followed periodically by a pediatrician.

Results: Primary CMV infection occurred during the first and second trimesters of pregnancy in 71 and 74 patients, respectively. Seven patients (4.8%) decided to terminate pregnancy because of prenatal findings and one neonate died because of CMV complications. Patients with first-trimester infection had infants with significantly more associated sequelae (either auditory damage or neurodevelopmental disabilities) than did patients with second-trimester infection (19.7% vs 5.6%, respectively; P = 0.01). Abnormal prenatal findings on ultrasound examination were associated with increased risk of sequelae. When both ultrasound and MRI findings were normal, the rate of sequelae was decreased to 15.6% for first-trimester infections and to 2.0% for second-trimester infections, partial hearing loss being the sequela in most cases. In the presence of abnormal ultrasound and/or MRI findings the risk was 25% and 16%, respectively, and in most cases the sequelae were deafness and neurodevelopmental delay. The rate of intrauterine growth restriction (IUGR) in the study group was 11.7% and was not affected by the time of onset of maternal infection. Isolated IUGR was not associated with increased risk of sequelae.

Conclusion: The risk of sequelae is higher following first-than second-trimester CMV infection. However, the risk of severe sequelae is significantly reduced in the presence of normal prenatal ultrasound and MRI findings.