Serum progesterone is a test to measures the amount of progesterone in the blood. Progesterone is a hormone produced mainly in the ovaries.

In women, progesterone plays a vital role in pregnancy. After an egg is released by the ovaries (ovulation), progesterone helps make the uterus ready for implantation of a fertilized egg. It prepares the womb (uterus) for pregnancy and the breasts for milk production.

Men produce some amount of progesterone, but it probably has no normal function except to help produce other steroid hormones.

See also: Pregnanediol

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

Your health care provider may tell you to stop taking drugs that may affect the test. Drugs that can interfere with the test include progesterone and birth control pills.

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

This test is done to diagnose or rule out disorders associated with abnormal progesterone levels, usually related to infertility or recurrent miscarriage. It may also be done to evalute bleeding in early pregnancy.

Progesterone levels vary depending on when the test is done. Blood progesterone levels start to rise midway through the menstrual cycle, continue to rise for about 6 to 10 days, and then fall if fertilization does not result.

Levels continue to rise in early pregnancy.

This following are normal ranges based upon certain phases of the menstrual cycle and pregnancy:

• Female (pre-ovulation): less than 1 ng/mL
• Female (mid-cycle): 5 to 20 ng/mL
• Male: less than 1 ng/mL
• Postmenopausal: less than 1 ng/mL
• Pregnancy 1st trimester: 11.2-90.0 ng/mL
• Pregnancy 2nd trimester: 25.6-89.4 ng/mL
• Pregnancy 3rd trimester: 48.4-42.5 ng/mL

Note: ng/mL = nanograms per milliliter

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Higher-than-normal levels may be due to:

• Pregnancy
• Adrenal cancer
• Ovarian cancer
• Congenital adrenal hyperplasia

Lower-than-normal levels are associated with:

• Amenorrhea
• Fetal death
• Threatened abortion
• Toxemia of pregnancy

Additional conditions under which the test may be performed:

• Ectopic pregnancy
• Infertility

There is very little risk involved with having your blood taken. Veins and arteries vary in size from one patient to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Rebar RW, Erickson GF. Menstrual cycle and fertility. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 256.

Lobo RA. Ectopic pregnancy: etiology, pathology, diagnosis, management, and fertility prognosis. In: Katz VL, Lentz GM, Lobo RA, Gershenson DM, eds. Comprehensive Gynecology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2007:chap 17.

Cunningham FG, Leveno KL, Bloom SL, et al. Implantation, embryogenesis, and placental development. In: Cunnigham FG, Leveno KL, Bloom SL, et al, eds. Williams Obstetrics. 22nd ed. New York, NY: McGraw-Hill; 2005:chap 3.