Progesterone Test

A progesterone test measures the level of progesterone in a sample of your blood. Progesterone is a hormone that's made mainly by the ovaries, which are two glands in the female reproductive system that contain eggs. Each month, progesterone prepares your uterus for pregnancy.

During the first half of a normal menstrual cycle, estrogen makes the lining of your uterus grow thicker. In the second half, an ovary releases an egg and your progesterone levels begin to rise. Progesterone gets the lining of your uterus ready for a fertilized egg to attach (implant) and grow into a fetus.

If you don't become pregnant, your progesterone levels will fall. The lining of your uterus will thin, and your uterus will get rid of the extra blood and tissue when your menstrual period begins. If you become pregnant, progesterone levels will continue to rise to support the pregnancy.

High levels of progesterone: Cause cells in the lining of your uterus to produce proteins that are necessary for the attachment of a fertilized egg.; Cause the creation of white blood cells that will make sure your immune system doesn't attack the fertilized egg.; Prevent the uterus from contracting (squeezing) and causing pre-term labor.; Play a role in the development of the placenta, an organ that grows in the uterus to provide nutrients and oxygen to the fetus.; Once the placenta is fully formed, it will make much of the progesterone you need for a healthy pregnancy.

Why this test is done

You may need a progesterone test if:

• You are having trouble getting pregnant. A progesterone test can help your health care provider see if your ovaries are releasing eggs (ovulating) normally.
• You are having fertility treatments.
• You are having abnormal bleeding when you're not pregnant.
• You have signs of low progesterone such as irregular menstrual periods, hot flashes, and trouble sleeping.
• You have signs of high progesterone such as vaginal dryness and bloating.

It's common to have your progesterone levels tested as part of a panel of tests you may get if you're pregnant. You may also need a progesterone test while pregnant if:

• You're having progesterone therapy to prevent a miscarriage.
• Your provider wants to check the health of your pregnancy because you have a higher risk for miscarriage or other pregnancy complications.
• You have signs of a miscarriage or ectopic pregnancy, such as cramps or bleeding.

How to prepare

You usually don't need any other preparations for a progesterone test. In certain cases, you may need to know the first day of your last menstrual period. Your provider will tell you if you need to stop taking any medicines before the test.

But never stop taking medicine unless your provider tells you.

Sample type

Blood

Other names for this test

serum progesterone, progesterone blood test, PGSN