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Fetal IgG Antibody Level (Serum/Plasma)

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

This test measures the amount of Immunoglobulin G (IgG), a type of antibody, in your baby’s blood. IgG helps protect against infections during pregnancy and early life.

Quick summary

["IgG levels help assess fetal immunity and identify potential risks of infections before birth."]

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

Key facts at a glance

LOINC
107456-6
Short code
DAT IgG-Sp Reag RBC Fetus-Imp
Synonyms
DAT IgG-Sp Reag RBC Fetus-Imp
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
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 This Test Is Done

Your healthcare provider may recommend this test if you have certain infections (like rubella, toxoplasmosis, or cytomegalovirus) during pregnancy. Low IgG levels in the fetus could mean it hasn’t built enough immunity from your antibodies, which may require extra precautions or treatment.

What to Expect During the Test

A small blood sample will be taken from your baby’s heel or umbilical cord during delivery or a scheduled procedure. The blood is sent to a lab for testing.

How the Results Are Used

Low IgG levels might prompt further evaluation, such as additional testing or monitoring to ensure your baby’s health. High levels are generally normal and indicate adequate protection.

Common Causes of Abnormal Results

Low IgG levels could be due to infections you had during pregnancy, certain medical conditions, or genetic factors. High levels may occur if your baby received extra antibodies (like from IVIG treatment).

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Antibody Level in Fetus

Frequently asked questions

What does a low IgG level mean for my baby?
A low IgG level may indicate your baby hasn’t received enough protection from infections through your antibodies. Your healthcare provider will discuss next steps, such as monitoring or additional interventions, based on your specific situation.
Will I need to take any special precautions if my IgG level is low?
If your IgG level is low, your provider may recommend extra precautions, like avoiding certain infections during early infancy or ensuring your baby receives recommended vaccines. Follow their guidance closely.
Can IgG levels change after birth?
Yes, IgG levels naturally decline after birth as your baby’s own immune system develops. Regular check-ups with your pediatrician can help track these changes and ensure your baby stays healthy.
  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