Immunological studies on human placental trophoblast components of potential utility for fertility regulation.

Results of immunization of both animals and humans against human chorionic gonadotropin (HCG) are reported. Since HCG plays a critical role in the earliest stage of pregnancy its neutralization should prevent nidation. HCG was conjuagted with tetanus toxoid to render it immunogenic as well as to confer the benefit of tetanus immunity. Toxicity studies revealed no undesirable effects in mice rats rabbits and monkeys. In initial clinical trials begun in 1974 antibody response was evoked in all subjects with a lag of 4-6 weeks. Menstrual cycles remained normal as did kidney liver pituitary cardiovascular and thyroid functions over a follow-up period of 16 months.