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Normoblasts (Nucleated Red Blood Cells), Fetal Blood — Number Fraction

Published: August 9, 2026Updated: August 17, 2026

A test that measures the fraction of normoblasts, or nucleated red blood cells, in fetal blood to help assess fetal blood-cell stress.

Quick summary

["An increased normoblast fraction in fetal blood may suggest fetal hypoxia, blood-cell destruction, infection, or placental stress."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
74463-1
Short code
Normoblasts NFr Bld Fetus
Synonyms
Normoblasts NFr Bld Fetus
Category
liver
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
84484
SNOMED
302774002
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What is this test?

Normoblasts are immature red blood cells that are normally released into the bloodstream during fetal development. This test measures their fraction in fetal blood, usually from an umbilical cord blood sample collected after birth.

Why might I need this test?

The result may help evaluate fetal oxygenation and identify conditions that increase blood-cell production. It is interpreted with other maternal, placental, and fetal findings rather than as a stand-alone measure of fetal well-being.

How is the test performed?

A laboratory counts the nucleated red blood cells in the fetal blood sample using a blood-counting method. Depending on the laboratory, the result may be reported as a fraction or in relation to the number of white blood cells.

How do I prepare for the test?

This test is generally performed on blood collected from the umbilical cord at delivery, so there is usually no separate patient preparation or fasting requirement. The delivery team and laboratory provide any specific collection instructions.

Reference range

Adult: 10-40 U/LN/A

Specimen: whole-blood

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Fetal normoblasts

Frequently asked questions

What are normoblasts?
Normoblasts are immature, nucleated forms of red blood cells. They are normally present during fetal development but usually are not found in the blood of healthy term newborns.
Does an increased result mean the baby has a specific condition?
No. Increased normoblasts can reflect several causes of fetal blood-cell stress, including low oxygen, blood-cell destruction, infection, or placental problems. Your clinician will interpret the result alongside the rest of the pregnancy and newborn evaluation.
Is this the same as a routine newborn blood count?
Not necessarily. A routine newborn blood count measures many blood-cell components, while this test specifically quantifies normoblasts in a fetal blood specimen. It may be used as part of a broader evaluation.
  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 17, 2026. · Read our editorial policy