Failure of daily measurements of hCG in urine to demonstrate a high rate of early embryonic mortality.

A radioimmunoassay employing beta hCG antiserum and tracer and hCG standard was used in an attempt to detect transient luteal phase rises in hCG in urine as evidence of occult pregnancy loss. It was found that the assay lacked specificity and detected 'hCG' surges at midcycle which were not confirmed using a more specific monoclonal antibody based immunoradiometric assay. Measurements on first morning urine samples across midcycle and throughout the luteal phase in 65 cycles from 36 women attempting to conceive revealed no evidence of transient hCG production in the 56 cycles which did not go on to a clinical pregnancy.