Maternal infection may result in no infection of the conceptus, resorption of the embryo, spontaneous abortion, stillbirth, or infection of the placenta and the fetus.11 Gestational age at the time of maternal infection is the most critical determinant of intrauterine transmission and fetal damage.11 A rubella IgM positive result in a single serum sample indicates an acute rubella infection or a fourfold rise in immunoglobulin G (IgG) in a serum sample taken sequentially and then assayed in pairs. The gene discussed is CD40LG; the disease is rubella.