Maternal high-dose valacyclovir and its correlation with newborn blood viral load and outcome in congenital cytomegalovirus infection

Background/objective: Currently, there is no validated treatment for fetal cytomegalovirus (CMV). Two studies suggest that high-dose maternal valacyclovir decreases fetal viral load and improves outcomes in moderately-symptomatic fetuses. We offered valacyclovir in cases of fetal infection lacking ultrasound abnormalities or with non-severe infection. Maternal tolerability, fetal outcome and newborn blood viral load were evaluated in pregnancies of mothers receiving valacyclovir.

Study design: We performed a case series including 8 pregnancies with fetal CMV classified as unaffected/mildly-moderately affected. Mothers received valacyclovir (8 g/24h) from fetal infection diagnosis to delivery. Standard newborn evaluation was performed, and viremia was determined in the first 48 h of life and compared according to length of maternal treatment and presence/absence of prenatal anomalies.

Results: Valacyclovir was administered at a median gestational age of 26.5 weeks (23.8-33.1) in 3 cases without fetal abnormalities, and 5 with mild/moderate abnormalities. Three were 3 first trimester primary infections, one non-primary infection, and in 4 the type of infection was unknown. Valacyclovir was well-tolerated. Fetal features did not progress. Three newborns were asymptomatic, and one was severely affected (bilateral chorioretinitis). The median newborn viral load (IQR) was 502 IU/mL (231-191781) with lower levels when maternal treatment was administered ≥10 weeks, and in cases without fetal abnormalities [median 234 IU/mL (228-711) vs. 4061 (292-510500) p = .18; and 234 IU/mL (228-379500) vs. 711 IU/mL (292-4061) p = .65, respectively], these differences being non-significant.

Conclusions: Fetal CMV lesions remained stable with high-dose maternal valacyclovir. Newborn viral load was unchanged despite treatment duration and fetal/neonatal abnormalities.

Summary: Fetal cytomegalovirus lesions remained stable with high-dose maternal valacyclovir. Newborn viral load was unchanged despite treatment duration and fetal/newborn abnormalities.