Background: Both primary and non-primary maternal cytomegalovirus (CMV) infection during pregnancy can lead to vertical transmission. We evaluated the proportion of maternal primary/non-primary infections among 26 babies with symptomatic congenital CMV infection born in Finland from 2000 to 2012.
Methods: We executed a database search on hospital records from all five university hospitals in Finland to identify infants with congenital CMV infection. The preserved maternal serum samples drawn at the end of the first trimester were analysed for CMV antibodies. Maternal infection was classified to be non-primary, if there was high avidity CMV immunoglobulin G (IgG) in the early pregnancy samples. Infection was considered primary in the case of either low avidity IgG (primary infection in the first trimester or near conception) or absent CMV IgG at the end of the first trimester (primary infection in the second or third trimester).
Results: The majority of the symptomatic congenital CMV infections (54%) were due to maternal non-primary infection, 27% due to maternal primary infection in the first trimester or near conception, and 19% during the second or third trimester. Long-term sequelae occurred in 59% of patients: in 6/7 after primary infection in the first trimester, in 0/5 after primary infection in the second or third trimester, and in 9/14 after non-primary infection.
Conclusions: In this register-based cohort, non-primary infections caused the majority of symptomatic congenital CMV infections, and resulted in significant morbidity.
Keywords: Congenital; cytomegalovirus; non-primary infection; primary infection; sequelae.