Version July 2025
Please read the Disclaimer at the end of this page.
What is a maternal serum alpha-fetoprotein test? —
A maternal serum alpha-fetoprotein test, or "MSAFP test," measures the amount of alpha-fetoprotein, or "AFP," in your blood.
AFP is a protein normally produced by your fetus (developing baby) during pregnancy. The protein enters your blood through the placenta. (The placenta is the organ that forms between you and your baby during pregnancy.) Different things can affect the level of AFP in your blood.
Doctors use an MSAFP test to help figure out if a fetus has an increased risk of having certain disorders, such as:
●Neural tube defects – This is when parts of the brain, spine, or spinal cord do not form normally. Spina bifida is an example.
●Certain genetic disorders, like Down syndrome – These are conditions that happen when a person is born with more or fewer chromosomes than usual. Chromosomes are tiny parts of cells that carry the plans that make our bodies the way they are. AFP is 1 of 4 substances doctors measure to screen for these disorders. When all 4 substances are measured, it is called a "quadruple," or "quad," test.
Why might I get an MSAFP test? —
Your doctor might order this test if you are pregnant and want to know how likely your fetus is to have certain disorders, such as a neural tube defect or Down syndrome. An MSAFP test is 1 of several tests that can help doctors figure this out.
An MSAFP test is usually done between 16 and 18 weeks of pregnancy. Some people have it as early as 15 weeks or as late as 20 weeks.
How do I prepare for an MSAFP test? —
You need to get a "blood draw." Your doctor or nurse will tell you where to go for this.
It might help to wear a short-sleeve shirt to your blood draw appointment. This makes it easier for the person drawing your blood to get to your arm.
What happens during a blood draw? —
A needle is used to take a small amount of blood from your arm (figure 1). Collecting the blood only takes a few minutes. The blood is then tested in a lab.
Tell the person who takes your blood:
●If you take "blood thinner" medicines or if you have a bleeding problem – They will make sure your bleeding is under control before you leave.
●If you have a latex allergy – Some of the supplies used for blood draws might contain latex.
●If you have a preferred arm to use
Most of the time, getting blood taken does not cause problems. You might have a little soreness or bruising where the needle went in.
What do my results mean? —
Your doctor or nurse will tell you when to expect your results, and will contact you with the results. Or if you use an online "patient portal," you might get an alert there when your results are ready.
If your MSAFP test shows any abnormal results, your doctor or nurse will talk to you about what to do next. It might also help to talk with an expert called a "genetic counselor." If the test results show your fetus has a high chance of having a disorder, you can choose to have a "diagnostic" test to find out for sure.
Patient education: Testing for Down syndrome during pregnancy (The Basics)
Patient education: Down syndrome (The Basics)
Patient education: Spina bifida (The Basics)
Patient education: Quadruple test (The Basics)
Patient education: Cell-free DNA prenatal screening (The Basics)
Patient education: Amniocentesis (The Basics)
Patient education: Chorionic villus sampling (The Basics)
Patient education: Should I have a screening test for Down syndrome during pregnancy? (Beyond the Basics)
Patient education: Down syndrome (Beyond the Basics)
Patient education: Amniocentesis (Beyond the Basics)
Patient education: Chorionic villus sampling (Beyond the Basics)
