Every month when ovulation occurs, the area in the ovary from where ovulation occurs develops into the corpus luteum or the "yellow body". The corpus luteum in the ovarya secretes the hormone called Progesterone which plays important roles in the menstrual cycle and in maintaining the early stages of pregnancy. Progesterone levels rise in the blood after ovulation and progesterone blood level in a normal pregnancy can be up to 10 times higher than when you are not pregnant. However, it's impossible to diagnose a pregnancy from progesterone levels. Only the pregnancy hormone hCG Human Chorionic Gonadotropin can make a pregnancy diagnosis.
As soon as the the egg is fertilized, the progesterone hormone stimulates the growth of blood vessels that supply the lining of the womb (endometrium) and stimulates glands in the endometrium to secrete nutrients that nourish the early embryo. Progesterone is responsible to get the tissue lining of the uterus ready to allow the fertilized egg to implant and helps to maintain the endometrium throughout pregnancy.
What are normal progesterone levels? What does progesterone do?
- Progesterone levels are low before ovulation
- Progesterone levels rise within 7-10 days after ovulation
- Before you ovulate, progesterone levels are usually below 10 ng/ml
- In the middle of the second half of the cycle, midcycle, about 7-10 days after ovulation, progesterone levels ate usually above 8-10 ng/ml.
- 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 from one top the other hour
- The hCG pregnancy hormone blood level is a better indicator of a viable pregnancy than the progesterone level.
- After 6 weeks of pregnancy the best indication that the fetus is doing well is to check the fetal heartbeat.
- Checking the progesterone level can be confusing because it's difficult to assess whether a low progesterone level means the pregnancy is already abnormal to begin with, or if the low progesterone is the cause of the bad outcome. Many doctors feel it's a failing pregnancy that triggers a low progesterone and that giving progesterone will not make a difference.
- Progesterone supplementation should be reserved to the following women: IVF, those with Injectable ovulation medications, those who have been shown to have immune reasons for miscarriages