Fetal head circumference measurement (ultrasound-derived)
This test measures the size of your baby’s head using ultrasound to help track growth during pregnancy. It’s a common part of prenatal care to monitor fetal development.
["Your doctor may use this test to check if your baby is growing at the expected rate."]
Key facts at a glance
- LOINC
- 11969-3
- Short code
- Fet Ulna Length US.meas
- Synonyms
- Fet Ulna Length US.meas
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- us-measured
- 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?
Doctors perform fetal head circumference measurements during prenatal ultrasounds to assess fetal growth and development. It helps identify potential issues early, such as growth restrictions or other complications that might require further evaluation.
When is this test typically done?
This test is usually conducted during routine prenatal ultrasounds, often between the 18th and 24th weeks of pregnancy, but may be repeated at other times if needed for monitoring.
What does the result mean?
The result provides a measurement of your baby’s head circumference in centimeters. While there’s no single ‘normal’ range (as it varies by gestational age), deviations from expected measurements can signal potential concerns that your healthcare provider will discuss with you.
How is this test performed?
The test involves a transvaginal or abdominal ultrasound. A gel is applied to your skin, and a transducer is used to capture images of your baby’s head. The measurement is taken from the outer edge of the baby’s skull to the outer edge of the opposite side.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance: Fetal head circumference is a critical indicator of fetal growth and health. Abnormal measurements may signal conditions like intrauterine growth restriction, chromosomal abnormalities, or other prenatal concerns that warrant additional testing or interventions.
Short name
Fetal Head Circumference (FHC)
Frequently asked questions
What does a low fetal head circumference mean?
What if my fetal head circumference is higher than expected?
Is fetal head circumference testing painful?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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