Alfa Fetoprotein test (AFP)
You have probably noticed that every woman prior conception or in her fist months of pregnancy is usually taking Folic Acid. It is a natural way to protect our baby from serious neural tube defects. Folic Acid is a reliable supplement that protects us, but we also need a little something more to be assured that our baby is growing healthy. This is where this test comes into play.
What is this test all about?
Alfa fetoprotein is a substance that is created in the fetal liver. Women who are pregnant have increased levels of this and with a simple blood sample; this AFP substance can help us examine the possibilities of whether this expected baby may have any congenital disorders such as spina bifida and anencephaly.
A blood sample is enough to check for spina bifida and anencephaly risks, but if you want to find other chromosomal problems such as Down syndrome or Edwards syndrome you have to combine the AFP test with a screening test. Through this test we can diagnose certain liver disorders or screen and monitor certain types of cancer.
The meaning of the levels …
Pregnant women have increased AFP levels because the baby passes certain amounts of AFP into the mother’s bloodstream. In this way if the baby has certain developing problems, these levels can be either very high or unusually low. In most cases we have abnormal levels and a completely healthy baby. That is why this test is not considered to be completely accurate. When we have unusual levels of AFP and a fine result from the screening test we have to repeat the test.
Sometimes the high levels do not mean that the baby has birth defect. It can indicate other problems that might happen in the last trimester of pregnancy like:
- Low amniotic fluid
- High blood pressure, nausea and swelling (preeclampsia)
- Intrauterine growth restriction
- An early disengagement of the placenta from the uterus
Low levels can indicate possibilities of a Down syndrome existence in the baby, but we need to run other test to prove that. We have other possible causes for low levels, such as:
- Physically undeveloped baby (smaller than normal)
- Overweight mother
- Diabetic mother
Proper ways to do this test
You have to be between 15 – 18 weeks pregnant in order to do this test. A blood sample is taken from your arm with a needle, collected and sent to a lab. You have to do this test at the right time. If you are one week late in your pregnancy the AFP level can be lower than normal. Consider leaving enough time for further steps like counseling or ultrasound if your levels are abnormal.
Abnormal AFP levels, What to do?
If you have abnormal levels you have to be sure that your due date is not mistaken. If you are sure about your due date and your AFP test is not normal that means you need further tests to explain these abnormal levels, such as:
- Ultrasound scan
- Amniocentesis ( sample taken from the fluid around the baby)
- Percutaneous umbilical blood sampling ( a way to get cells from the baby’s blood )
If these tests show that your baby has developing problems, you should talk to your health care provider about the further steps and choices of treatment. With an early diagnosis from the AFP test your baby can benefit, because there are treatments and therapies that can improve your baby’s outlook.