Transmission of cytomegalovirus to mothers by infected infants: another reason to prevent transfusion-acquired infections.

Forty-seven percent of mothers who were seronegative to cytomegalovirus at the time an infected infant entered their home seroconverted within 12 months of exposure. In contrast the seroconversion rate was 2.4% among mothers of uninfected infants discharged from the same nursery and ranges from 1.4 to 2.6% in studies reported by others. All infants shed virus throughout the follow-up period. It was not possible to determine whether length of exposure or the age of the child were important factors in determining risk of seroconversion; however, most seroconversions occurred after the child had been home for 4 months or longer. Two mothers became pregnant while still seronegative. Transfusion-acquired infections are one avoidable source of transmission from infant to mother. Seronegative mothers in continuing contact with excreting infants are at risk of acquiring a cytomegalovirus infection and of transmitting it to their fetus should they become pregnant.