Abstract: The present invention provides antibodies which specifically bind early conception factor, which can be found in body fluids of animals including but not limited to the cow, cat, dog, horse, human, sheep, and pig. The invention provides methods for detecting conception or the absence of conception in an animal, the latter being recognized by the absence of early conception factor in a suitable body fluid collected from the animal. Apparati for detecting early conception factor in a body fluid from an animal comprising the antibodies which specifically bind early conception factor are also provided.