Efficacy of antibodies generated by PR-β-hCG-TT to terminate pregnancy in baboons: Its reversibility and rescue by medroxyprogesterone acetate

Antibodies produced by the vaccine Pr-β-hCG-TT in monkeys were effective in terminating pregnancy in baboons on passive administration. The animals returned to cyclicity soon after the onset of vaginal bleeding. Fertility was regained. Globulins from non-immunized control monkeys in amounts, volume and injection schedule similar to those employed for passive termination did not intercept pregnancy. The abortifacient action of anti-CG antibodies could be counteracted by administration of medroxyprogesterone acetate.