In contrast, in a prospective cohort study of 2193 low-risk pregnant women (i.e., pregnant women not referred because of positive results for CMV IgM), the prediction accuracy for congenital CMV infection of maternal serological screening, based on CMV IgG avidity index (cutoff values: ≤45% or < 35%), was similar to that based on CMV IgM (>1.2 index) [14]. This evidence concerns the gene CD40LG and cytomegalovirus infection.