During the second trimester, your healthcare provider will likely recommend some screening tests. One of these tests checks the level of alpha-fetoprotein produced by your baby as a way to assess your little one’s risk of a neural tube defect or a chromosomal abnormality.

This screening test is called the maternal serum alpha-fetoprotein test or MSAFP for short.

To help you understand what this test is all about, we’ve addressed some frequently asked questions about the maternal serum alpha-fetoprotein screening, including how it’s done and what the results can tell your healthcare provider about your little one’s health.

What Is Maternal Serum Alpha-Fetoprotein?

Alpha-fetoprotein (AFP) is a protein that is produced by your baby as he develops during your pregnancy.

Although it’s the baby who produces AFP, it becomes present in the mother's bloodstream as well. That’s why it’s called a maternal serum alpha-fetoprotein test.

Too much AFP in your body may indicate that your baby is at risk of a neural tube defect, like spina bifida, which results from incomplete development of the brain and spinal cord. Too little may indicate your little one has a chromosomal abnormality, like Down syndrome.

What Is a Maternal Serum Alpha-Fetoprotein Screening Test?

A maternal serum alpha-fetoprotein screening is a type of prenatal blood test that measures the levels of MSAFP in your body. This test is commonly offered to all moms-to-be in the second trimester as part of their prenatal care.

The test helps your healthcare provider assess your little one’s risk of certain medical conditions.

If you’re unsure about whether you’d like this screening test, ask your provider for advice on what’s recommended for your situation so that you can make an informed choice.

When Is an MSAFP Test Done?

A maternal serum alpha-fetoprotein test is typically done in the second trimester between 16 and 18 weeks of pregnancy.

It's often done as part of a quadruple screening test (or quad screen), which besides testing for MSAFP also tests for the pregnancy hormones hCG, estriol, and inhibin-A.

What Is an Integrated Screening?

Results from your first trimester screening, which includes a nuchal translucency screening, combined with the results from the quadruple screen, which includes the MSAFP test, are looked at together by your healthcare provider to get a more complete picture of your little one’s health. These combined tests are sometimes referred to as an integrated screening.

By looking at the results of all these prenatal scans and tests together, your healthcare provider can try to determine whether your baby is at risk of being born with certain medical conditions. These may include a neural tube defect such as spina bifida or chromosomal abnormalities such as Down syndrome (trisomy 21) and trisomy 18.

What Do the Maternal Serum Alpha Fetoprotein Levels Mean?

High levels of MSAFP could indicate a neural tube defect such as spina bifida, whereas low levels could a chromosomal abnormality such as Down syndrome. Your healthcare provider has the expertise to assess the level of risk, and will go over the test results with you.

What Happens if Your MSAFP Test Result Is Outside the Normal Range?

Taking into account other factors such as your age, your healthcare provider can use the MSAFP test results to determine how high or low the risk is of your baby having a certain medical condition.

Keep in mind that each testing laboratory may have a different range for determining the risk so it’s best to ask your healthcare provider to interpret the results for you.

Remember that the MSAFP test only helps your healthcare provider to assess your baby’s risk of being born with certain medical conditions.

It’s worth noting that the chance of getting a positive result is very low.

If, however, your healthcare provider determines your baby is at risk, she may recommend further diagnostic tests, such as amniocentesis (tested in the second trimester), so that she can make a diagnosis.

Amniocentesis requires a sample of your amniotic fluid. Your provider will be able to explain the risks and benefits of these diagnostic tests to you so that you can decide how you wish to proceed.

It’s normal to want reassurance that everything is OK with your little one. A screening test like the MSAFP can give your healthcare provider important information about your baby that contributes to an overall assessment of your little one’s health.

In the rare chance that a screening test does come back positive, your healthcare provider will be able to explain what the results mean. Additional diagnostic tests can then be done, if you’d like. Your provider will be there with you every step of the way to give you personalized guidance and help you make informed choices that you feel comfortable with.

As you progress through your pregnancy, find out what else is in store each week, month, and trimester with our useful and informative pregnancy calendar.

How we wrote this article

The information in this article is based on the expert advice found in trusted medical and government sources, such as the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists. You can find a full list of sources used for this article below. The content on this page should not replace professional medical advice. Always consult medical professionals for full diagnosis and treatment.