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Serum alpha-fetoprotein (AFP) measured during pregnancy to assess fetal development and screen for birth defects

Published: August 9, 2026Updated: August 16, 2026

This blood test checks levels of alpha-fetoprotein, a protein made by the fetus, to help monitor fetal health and detect certain birth defects or genetic conditions.

Quick summary

["AFP screening helps identify risks early for planning further prenatal care or testing."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
85719-3
Short code
GA (weeks)--at cess of preg
Synonyms
GA (weeks)--at cess of preg
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why is this test done during pregnancy?

Your healthcare provider may recommend this test between 14 and 22 weeks of pregnancy to screen for chromosomal abnormalities (like Down syndrome) or neural tube defects (like spina bifida). It can also help assess fetal growth and development.

How is the test performed?

A blood sample is taken from a vein in your arm. You may feel a small pinch when the needle is inserted, but the procedure usually takes only a few minutes.

What does the test result mean?

Higher-than-normal AFP levels may suggest certain birth defects or chromosomal issues, while lower levels could indicate other concerns like miscarriage or ectopic pregnancy. Your results will be reviewed by a healthcare provider to interpret them accurately.

What are the possible risks or side effects?

There are generally no major risks with this blood test. Possible minor side effects may include slight bruising, swelling, or a slight sting at the injection site.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: Alpha-fetoprotein (AFP) is a critical marker in prenatal screening. Elevated AFP levels can signal neural tube defects or other genetic conditions, prompting additional diagnostic tests like amniocentesis or ultrasound. Lower-than-expected AFP may warrant further evaluation to rule out pregnancy complications.

Short name

Pregnancy AFP screening test

Frequently asked questions

Why did my doctor order this test?
Your doctor may have recommended it to screen for birth defects, monitor fetal health, or assess pregnancy risks based on your medical history or gestational age.
What should I do if I have abnormal results?
If your AFP levels are outside the expected range, your healthcare provider will discuss next steps, which may include additional tests or ultrasounds to further evaluate your pregnancy.
Can I eat or drink before this test?
You can eat and drink normally before the test, as it does not require fasting.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy