CD40LG and infection: Given that placental pathology was suggestive of a damaged syncytiotrophoblast barrier and that we also observed high maternal levels of anti-N IgM and detectable anti-HA IgM in the cord at the same level as in maternal plasma, these findings likely represent aberrant transplacental transfer of IgM in the setting of placental compromise,54 rather than a specific elevation of IgM due to in utero infection.