Long-term follow-up of children born to women immunized with tetanus toxoid during pregnancy.

Ten years after transplacental immunization with tetanus toxoid, the antibody responses of the immunized children to a booster immunization with 5 Lf tetanus toxoid did not differ from those of the control children. The tetanus toxoid-stimulated lymphocyte proliferative responses showed that there was no tolerance to tetanus toxoid induced by transplacental immunization, and the stimulation indices suggested that there may be some long-term memory for tetanus toxoid among the T lymphocytes in children who had been transplacentally immunized by maternal immunization with a standard dose of tetanus toxoid.