Frequently asked questions: Alpha-fetoprotein of pregnancy (AFP)

pregnancy alpha fetoprotein

Usually, in the second trimester of pregnancy, doctors offer to undergo screening, which includes an analysis for alpha-fetoprotein, or AFP for short. Alpha-fetoprotein is a protein produced in the baby’s body in the womb, and its analysis allows you to assess the risk of a neural tube defect and chromosomal abnormalities.

To help you understand what this test is, we have collected in one article answers to the most popular questions about the AFP test: how it is done and what information your doctor gets from the results.


What is alpha-fetoprotein?

Alpha-fetoprotein (AFP) is a protein produced in the body. Although the protein is produced by the baby, it is found in the mother’s blood.

If, according to the results of a blood test, alpha-fetoprotein is elevated, this may indicate the risk of developing a neural tube defect, for example, spina bifida – an abnormal development of the spinal cord. Too low a concentration can be a sign of a chromosomal abnormality, such as Down syndrome.


What is an alpha-fetoprotein test?

An alpha protein test is a blood test as part of a prenatal screening that measures the level of AFP in your blood. Usually it is prescribed to expectant mothers in the second trimester of pregnancy (at 15-20 weeks).

With this analysis, the doctor can assess the child’s risk of developing a number of abnormalities.

If you are not sure if you want to take this test, consult your doctor, which is recommended in your case, in order to make an informed choice.


When to get tested for alpha-fetoprotein?

Alpha protein testing is usually done in the second trimester between weeks 16 and 18 .

Usually, a biochemical blood test in the framework of screening, in addition to AFP, includes three more indicators: the hCG hormone, inhibin A, and free estriol. This analysis is also called the quadruple test.


What is Comprehensive Screening?

To get a complete picture of your baby’s health, the doctor will look at the first trimester screening results, which included an assessment of TST (collar space), and the second trimester screening results, which included an AFP test.

This is sometimes referred to as comprehensive screening.

After evaluating the results of prenatal ultrasounds and blood tests, your doctor may try to determine if your baby is at risk of developing abnormalities. These may include: a neural tube defect such as spina bifida or chromosomal abnormalities such as Down syndrome (trisomy 21) and Edwards syndrome (trisomy 18).


What does the alpha-fetoprotein level indicate?

A high level of AFP can mean a risk of a neural tube defect such as spina bifida, a low level can mean a risk of a chromosomal abnormality such as Down syndrome. Your doctor will be able to assess the level of risk and comment on the results for you.


What if AFP readings are out of range?

By analyzing a number of factors, such as age, and the results of AFP, the doctor can assess the level of risk of congenital diseases in the baby.

Please note that different laboratories may use different reference values ​​to determine risk, so it is best to consult your doctor for an explanation of the results.

The analysis for alpha-fetoprotein is only an auxiliary study, on the basis of which the doctor can assess the level of risk of congenital diseases.

It should be noted that the chance of a positive outcome (that is, having a high risk) is extremely low.

If your doctor thinks there is still a risk, he or she may order additional tests, such as amniocentesis (performed in the second trimester) to determine an accurate prognosis.

Amniocentesis involves drawing a small amount of amniotic fluid. Your doctor will explain the benefits and risks of this study so you can make an informed decision.

The desire of the expectant mother to receive an assurance that everything is in order with the baby is natural. The AFP test is a source of important information for your doctor, which is necessary for an overall assessment of your baby’s health.

In rare cases, the test result will indicate the risk of illness: your doctor will explain how the results are interpreted. Additional research can be done if you wish. Your doctor will support you with recommendations tailored to your individual situation and will help you make informed decisions.