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Estimated Gestational Age Based on Maternal Serum Biomarkers (Screening for Due Date)

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

This test measures certain substances in your blood to help estimate how far along you are in your pregnancy and confirm your due date. It’s often used alongside ultrasound measurements.

Quick summary

["This screening helps confirm pregnancy timing and supports planning for delivery."]

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

Key facts at a glance

LOINC
53693-8
Short code
GA Est from conception date
Synonyms
GA Est from conception date
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
estimated-from-conception-date
CPT
85610
SNOMED
396252006
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

What Does This Test Measure?

Your blood sample is analyzed for specific biomarkers that reflect early pregnancy development. These markers help assess the accuracy of your estimated due date, especially in cases where ultrasound results may not be definitive.

Why Is This Test Ordered?

Doctors may order this test if your ultrasound results are unclear, if you’re at higher risk for complications affecting gestational age, or if you’re seeking confirmation of your pregnancy timeline for planning purposes.

How Is the Test Performed?

A simple blood draw is taken from a vein in your arm. The sample is sent to a lab for analysis using immunoassay techniques to detect and measure the biomarkers.

What Are the Possible Results?

Results are compared against established reference ranges for gestational age biomarkers. A precise due date estimate is provided, though individual variations may occur. Your healthcare provider will discuss the findings with you.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: serum

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Gestational Age Biomarker Screening

Frequently asked questions

How accurate is this test for determining my due date?
This test is highly accurate for confirming gestational age, especially in early pregnancy. However, it’s typically used alongside ultrasound measurements for the most precise due date estimate. Your healthcare provider will weigh both results to determine the best timeline for delivery.
What if my test results show a discrepancy from my ultrasound?
Discrepancies between test results and ultrasound are not uncommon. Your provider may re-evaluate both findings, consider additional tests, or adjust your due date based on the most reliable data. Open communication with your healthcare team is key to understanding the best course of action.
Can I fast or avoid certain foods before this test?
No special preparations are needed for this test. You can eat and drink normally before the blood draw, as it does not involve fasting or dietary restrictions.
  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