Naturally occurring anti-hCG/LH antibodies as a cause of early abortion.

Anti-hCG/LH autoantibodies were found in the serum of an infertile woman a few days after an abortion which occurred after 46 days of amenorrhea. The antibody titer increased for approximately 4 more weeks, and then declined to low levels during a 14-month anovulatory period, after which regular menses resumed. Immunoglobulins isolated from a pool of serum obtained during the postabortion period neutralized the activity of both hCG and LH in an in vivo bioassay, and the binding affinity of the antibodies toward both hormones was high. When menses were resumed, there was a considerable reduction of the affinity toward LH. The variations in antibody titers and/or affinities can explain the sequence of fertilization, abortion, anovulatory period, and normalization of menses.