Phbldcfetus
A test that measures the acidity level in a baby's blood during labor to check if the baby is getting enough oxygen.
{"Measures blood pH from a small fetal scalp sample during labor","Helps doctors assess if the baby is receiving adequate oxygen","Normal fetal blood pH is above 7.25; lower values may indicate distress","Results help guide delivery decisions","The test is quick and provides important safety information"}
Key facts at a glance
- LOINC
- 33913-5
- Short code
- pH BldC Fetus
- Synonyms
- pH BldC Fetus
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- not specified
- Ref low
- 7.25
- Ref high
- 7.35
- Critical range
- 7.2 not specified – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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 is this test?
The fetal blood pH test measures how acidic the baby's blood is during labor. It is performed by taking a small sample of blood from the baby's scalp using a special device. This test helps doctors understand whether the baby is getting enough oxygen and how well the baby is tolerating the labor process.
How is the test performed?
During a vaginal examination, the doctor or midwife uses a small instrument called a fetoscope or amnioscope to view the baby's scalp. A tiny prick is made on the scalp, and a small amount of blood is collected into a thin tube. The sample is then analyzed immediately using a blood gas analyzer to measure the pH level. The procedure takes only a few minutes.
What do the results mean?
Fetal blood pH is measured on a scale from 0 to 14, with 7.35-7.45 being normal for adults. For babies, a pH of 7.25 or higher is generally considered normal. A pH below 7.20-7.25 may indicate fetal acidosis, meaning the baby is not getting enough oxygen and may be in distress. Your healthcare provider will interpret the results along with other monitoring information to decide on the best course of action.
Is the test safe?
The fetal scalp blood sampling is generally considered safe, though it does carry minor risks such as slight bleeding from the puncture site or a very small risk of infection. The procedure is only performed when necessary, such as when electronic fetal monitoring shows abnormal heart rate patterns. The benefits of obtaining important information about your baby's well-being usually outweigh these small risks.
Reference range
7.25-7.35not specified
No fasting required; obtained via fetal scalp sampling during labor under obstetric indications only
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings2
Frequently asked questions
Does this test hurt the baby?
How long does it take to get results?
Can I request this test?
What happens if the pH is low?
Are there alternatives to this test?
Sources
- 1
- 2
- 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