The alpha-fetoprotein test is a blood test that measures the level of alpha-fetoprotein in the blood of a pregnant woman. It’s a part of a series of prenatal tests called multiple marker or triple screen tests. These are performed during the second trimester of a pregnancy. That said, even women who aren’t pregnant get the AFP test. It can give critical information about the fetus and also shed light on certain health conditions.

Why is the alpha-fetoprotein test, and why is it done?
The liver of a developing fetus usually produces a type of protein called alpha-fetoprotein. Some amount of this protein travels through the placenta into the mother’s blood. The AFP test is done to check the amount of alpha-fetoprotein in the mother’s blood. Too much or little of this protein may be a sign of a birth defect. These defects can include open neural tube defects, such as spina bifida, and chromosomal abnormalities, such as Down syndrome. The test can also tell if the mother is pregnant with more than one baby at a time.

Sometimes, doctors may prescribe the AFP test to non-pregnant women if they want to check for conditions like cirrhosis, hepatitis, or liver cancer. Additionally, the test can help detect other types of cancers, such as testicular cancer, ovarian cancer, biliary tract cancer, stomach cancer, and pancreatic cancer.

How is the test performed?
To do an alpha-fetoprotein test, blood is drawn from a vein in the arm or the hand using a small needle. It’s a relatively painless process and takes only a few minutes. The collected blood is then sent to a laboratory for analysis. The results of the test are typically available within one to two weeks, depending on the lab. Note that pregnant or non-pregnant women don’t need any special preparation before the test.

When is the test done?
In general, the AFP test is done between the 14th and 22nd weeks of pregnancy. However, the results are most accurate when the test is performed between the 16th and 18th week. Note that since the levels of alpha-fetoprotein vary during pregnancy, doctors recommend that pregnant women know their exact date of conception for more reliable results.

Who should get the alpha-fetoprotein test?
The American Pregnancy Association recommends all pregnant women get the AFP test. It is especially important for those at a greater risk of giving birth to children with birth defects. These include women who are 35 or older, those who have a family history of birth defects, or those who have diabetes.

Are there any risks in the test?
The test is safe for both the mother and the fetus, and carries no significant risks. The patient may only temporarily feel slight pain or bruising at the spot where the needle is inserted. In rare cases, the vein can become swollen after drawing blood. To reduce swelling, one can consult their doctor and apply a warm compress several times per day.

What do the test results mean?
It’s worth pointing out that the AFP test is only a screening test and not a diagnostic test. The test results give doctors quite a few insights. If a woman has higher-than-normal alpha-fetoprotein levels, it means she may deliver a baby with open neural tube defects, such as spina bifida or anencephaly. Spina bifida is a condition in which bones of the spine don’t close around the spinal cord, while anencephaly prevents normal development of the brain and the bones of the skulls.

If the results show unusually low alpha-fetoprotein levels, it indicates the probability of a chromosomal abnormality in the fetus, such as Down syndrome, a condition with mild to severe intellectual and developmental problems.

Abnormal levels of alpha-fetoprotein can also mean that the women will give birth to more than one baby in a single pregnancy.

For non-pregnant women and men, unusually high levels of alpha-fetoprotein may be a sign of liver diseases or certain forms of cancers.

It’s important to keep in mind that the abnormal test results don’t mean the child will certainly be born with specific issues. Sometimes, the result can be false-positive, or a woman’s due date can be wrong—the baby can be perfectly healthy even when results indicate problems. Therefore, doctors typically conduct more tests to make an accurate diagnosis if the alpha-fetoprotein test results are abnormal. One such test is amniocentesis, which is more invasive and gives a more accurate diagnosis of Down’s syndrome and other birth disorders. In amniocentesis, amniotic fluid is removed from the uterus for testing. Invasive procedures during pregnancy may carry a risk of miscarriage, so it’s crucial to consult with a healthcare professional before signing up for any procedure.