The B-Bridge Progesterone Immunoassay kit is designed to quantitatively measure Progesterone present in extracted dried fecal samples, urine and tissue culture media samples. A progesterone standard is provided to generate a standard curve for the assay. Standards or diluted samples are pipetted into a clear microtiter plate coated with an antibody to capture mouse antibodies. A progesterone-peroxidase conjugate is added to the standards and samples in the wells. The binding reaction is initiated by the addition of a monoclonal antibody to progesterone to each well. After a 2 hour incubation the plate is washed and substrate is added. The substrate reacts with the bound progesterone-peroxidase conjugate. After a short incubation, the reaction is stopped and the intensity of the generated color is detected in a microtiter plate reader capable of measuring 450nm wavelength.