Abstract
Anti-progesterone monoclonal antibody injected intraperitonially as a single dose(100$\mu\textrm{g}$) 48hours post coitum(p.c.) almostly blocked pregnancy in ICR mice. The blocking rate of pregnancy in mice treated with antibody were decreased proportionally according to dose of antibody injected ; the rate were 60%, 57% and 17% as the antibody of 10$\mu\textrm{g}$, 50$\mu\textrm{g}$ and 100$\mu\textrm{g}$ were injected respectively. Blood serum progesterone concentration was greatly increased(21 times) after treatment(100$\mu\textrm{g}$), by virtue of high-affinity binding by antibody in circulation of non-pregnant mice in coompared with that of control group at day 10 p.c.. The concentration was about 1.6 times higher in the pregnant mice than in the non-pregnant mice in antibody treated group. In control group, the progesterone concentration was over 7 times higher in the pregnant mice than in non-pregnant mice at day 5 p.c..