A method for predicting pregnancy outcome includes measuring blood levels of hCG-hg and progesterone in a pregnant woman, determining a rate of change of progesterone levels from the blood measurements, determining at least a qualitative direction of change of hCG-hg levels from the blood measurements, comparing the determined rate of change of progesterone levels with a pre-established reference value, and determining at least a qualitative likelihood of a term pregnancy and a failed pregnancy for the woman from the qualitative direction of change of hCG-hg levels and the determined rate of change of progesterone levels relative to the pre-established reference value. The rate of change of progesterone is determined by formula as a number of days for progesterone to double.