Human cytomegalovirus (CMV) is the most common infection acquired before birth. In the US, about 1 of every 150 to 200 infants (0.5%-0.67%) are born with congenital CMV (cCMV). About 1 in 5 infants with cCMV infection will experience long-term effects such as sensorineural hearing loss (SNHL) and neurodevelopmental delays. The role of cCMV in the development of autism spectrum disorders (ASD) has been suggested for decades but remains a compelling unanswered question. Moderna is currently developing a CMV vaccine (mRNA-1647) for use in the prevention of primary CMV infection in men and women 16 to 40 years of age. To further generate evidence for the need of a preventative vaccine, a more detailed understanding of the natural history of cCMV from birth is needed. Likewise, understanding the role of maternal serostatus and seroconversion in the development of conditions such as ASD and assessing early childhood development is needed.