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pO2 Cord Blood arterial

Blood Gases

UA pO2Umbilical arterial pO2

Review status

Currently under review

Pending specialist review and validation.

What it shows

This test measures the partial pressure of oxygen in blood taken from the umbilical artery of the cord immediately after birth. It reflects how much oxygen was available to your baby just before delivery, when the placenta was still doing the work of gas exchange instead of the lungs.

It is typically performed as part of a blood gas analysis along with pH, carbon dioxide, and base excess. The arterial sample represents the baby’s status, while the umbilical vein more closely reflects placental oxygen. Together, these values help your care team understand the baby’s condition around the time of birth.

Why it matters

Arterial cord pO2 helps assess how well your baby was oxygenated during labor and delivery. It can support the evaluation of events such as cord compression, placental problems, or other conditions that may limit oxygen delivery. Results are considered alongside the clinical picture, including the baby’s tone, breathing, heart rate, and other cord blood gas values.

Your team may order this test after a complicated labor, concerning fetal heart rate patterns, operative delivery, or when the baby needs extra support after birth. The information can guide immediate care for your newborn and can also assist with understanding what happened during labor and planning future care if needed.

Understanding your results

If arterial cord pO2 is lower than expected, it can indicate that your baby had limited oxygen just before birth. Higher values can occur with maternal oxygen therapy or if the sample was exposed to air. Clinicians interpret this number together with pH, carbon dioxide, base excess, and the baby’s clinical condition to decide whether any treatment or extra monitoring is needed.

If results do not match how your baby looks and feels, your team may confirm findings with another blood sample from the baby or repeat testing. Most of the time, care decisions are based on the whole picture rather than a single number. Your clinician will explain what the results mean for your baby and whether any follow up is recommended.

Reference ranges

4.1 – 31.7 mmHg
All sexes
0 days – 150 years

Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.

Factors that could impact pO2 Cord Blood arterial

  • Sample handling and air exposure

    Air bubbles or a loose cap can falsely raise oxygen readings, while delays in analysis or inadequate icing can lower them. Proper heparinization and prompt processing are important.

  • Correct vessel and timing

    Arterial and venous cord samples differ. Mislabeling the vessel, delayed clamping, or sampling long after delivery can change measured oxygen levels.

  • Maternal oxygen and environment

    Supplemental oxygen given to the mother can increase cord oxygen values, while high altitude or maternal respiratory conditions can reduce them.

  • Labor and placental factors

    Cord compression, placental abruption, uterine hyperstimulation, or prolonged labor can limit oxygen delivery to the fetus and affect the result.

  • Medications and anesthesia

    Maternal opioids, magnesium sulfate, and some anesthetic agents may influence fetal oxygenation or gas exchange and can impact interpretation.

  • Specimen integrity and identification

    Clots, insufficient volume, or mixing arterial and venous blood can distort the true value, so accurate collection and labeling are essential.

2026

References

  1. McGill University Health Centre. (2018, April 17). pO2 Cord Blood arterial (Task CD 2060895). Laboratory reference ranges.
  2. Royal College of Obstetricians and Gynaecologists. (2014). Umbilical cord blood gas analysis (Scientific Impact Paper No. 39).
  3. Weiner, G. M., Zaichkin, J., & American Academy of Pediatrics and American Heart Association. (2021). Textbook of Neonatal Resuscitation, eighth edition. Neonatal Resuscitation Program guidelines.