Fetal Weight Estimation Using Uterine Size Measurement (Ultrasound)
This test uses ultrasound to estimate the weight of your baby during pregnancy based on measurements of your uterus. It helps monitor fetal growth and development.
["Ultrasound fetal weight estimation helps track your baby’s growth and ensures timely medical attention if needed."]
Key facts at a glance
- LOINC
- 11727-5
- Short code
- Fet Weight US+est
- Synonyms
- Fet Weight US+est
- 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-estimated
- 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
How the Test Works
Your healthcare provider uses ultrasound imaging to measure specific anatomical landmarks in your uterus, such as the biparietal diameter, head circumference, or abdominal circumference. These measurements are compared to standardized growth charts to estimate fetal weight. The test is typically performed between 18 and 40 weeks of gestation.
Why It’s Done
This test is often used to monitor fetal growth, especially in high-risk pregnancies or when there are concerns about potential growth restrictions. It can also help determine the due date or assess readiness for birth in certain cases.
Preparation
No special preparation is needed. You may be asked to drink water beforehand to help your bladder fill, which can improve the ultrasound image quality. Wear comfortable clothing with no tight waistbands.
What to Expect During the Test
You’ll lie on your back on an exam table while a gel is applied to your abdomen. A transducer (a handheld device) is placed on your skin to send and receive sound waves. The technician will move the transducer around to capture images of your baby’s head, chest, and abdomen. The process usually takes about 20–30 minutes.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Estimating fetal weight helps identify potential issues early, such as intrauterine growth restriction (IUGR), which may require closer monitoring or interventions like nutritional support or medical evaluation. It also supports decisions about timing of delivery in cases where the baby may be approaching term.
Short name
Fetal Weight Estimation
Frequently asked questions
Is fetal weight estimation always accurate?
When might I need this test?
What happens if the test shows a concern about fetal weight?
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