Early detection of pregnancy in rhesus and stump-tailed macaques (Macaca mulatta and Macaca arctoides). Evaluation of two radioimmunoassays and a hemagglutination inhibition test.

Chorionic gonadotropin (mCG) in serum and urine of monkeys was determined by a radioimmunoassay and hemagglutination inhibition (HAI subhuman primate tube test for pregnancy). HAI-positive pregnancy tests coincided fully with the mCG excretion patterns as determined by RIA (oLH beta system). The least reliable system was the hCG-beta RIA. The HAI test allowed accurate prediction of the parturition date.