Progesterone levels are low before ovulation, usually below 10 ng/ml. Progesterone levels rise, usually above 8-10 ng/ml, within 7-10 days after ovulation in the middle of the second half of the cycle (mid-cycle).
Progesterone levels are usually higher when you are pregnant, but cannot be used to test for pregnancy. Even in a non-pregnant patient they can reach 20 ng/ml. After ovulation, progesterone levels should be greater than 10 to 12 ng/ml to have a better chance of a good pregnancy outcome.
Progesterone levels drop when you are not pregnant. The progesterone drop induces the menstrual period. Progesterone levels fluctuate a lot, even on the same day and can even vary by the hour.
The progesterone blood level in a normal pregnancy can be up to 10 times higher than when you are not pregnant.