Health & Pregnancy

An alpha-fetoprotein (AFP) blood test checks the level of AFP in a pregnant woman's blood. AFP is a substance made in the liver of an unborn baby (fetus). The amount of AFP in the blood of a pregnant woman can help see whether the baby may have such problems as spina bifida and anencephaly. An AFP test can also be done as part of a screening test to find other chromosomal problems, such as Down syndrome (trisomy 21) or Edwards syndrome (trisomy 18). An AFP test can help find an omphalocele, a congenital problem in which some of the baby's intestines stick out through the belly wall.

Normally, low levels of AFP can be found in the blood of a pregnant woman. No AFP (or only a very low level) is generally found in the blood of healthy men or healthy, nonpregnant women.

The level of AFP in the blood is used in a maternal serum triple or quadruple screening test. Generally done between 15 and 20 weeks, these tests check the levels of three or four substances in a pregnant woman's blood. The triple screen checks alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and a type of estrogen (unconjugated estriol, or uE3). The quad screen checks these substances and the level of the hormone inhibin A. The levels of these substances-along with a woman's age and other factors-help the doctor estimate the chance that the baby may have certain problems or birth defects.

Screening tests are used to see what the chance is that your baby has a certain birth defect. If a screening test is positive, it means that your baby is more likely to have that birth defect and your doctor may want you to have a diagnostic test to make sure.

Pregnancy: Should I Have the Maternal Serum Triple or Quadruple Test?

Men, nonpregnant women, and children

In men, nonpregnant women, and children, AFP in the blood can mean certain types of cancer, especially cancer of the testicles, ovaries, stomach, pancreas, or liver are present. High levels of AFP may also be found in Hodgkin's disease, lymphoma, brain tumors, and renal cell cancer.

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Why It Is Done

The AFP test is done to:

• Check the developing baby (fetus) of a pregnant woman for brain or spinal problems (called neural tube defects). Such defects occur in about 2 out of every 1,000 pregnancies.¹ The chance of a neural tube defect in a baby is not related to the mother's age. Most women whose babies have neural tube defects have no family history of these problems.
• Check the developing baby (fetus) of a pregnant woman for Down syndrome.
• Find certain cancers, especially cancer of the testicles, ovaries, or liver. But up to half of the people with liver cancer do not have high AFP levels.
• Check how well treatment for cancer is working.
• Check for liver cancer (called hepatoma) in people who have cirrhosis or chronic hepatitis B.