What is the normal fetal oxygen saturation (FSpO2) range?

What is the normal fetal oxygen saturation (FSpO2) range?

• A. 40% - 70%
• B. 90% - 100%
• C. 70% - 90%
• D. 20% - 40%

Answer: (A)

In utero, oxygen delivery to the fetus occurs through the placenta, and fetal hemoglobin binds oxygen with higher affinity, so arterial oxygen saturation is lower than after birth. The normal fetal oxygen saturation range is about 40–70%, reflecting the typical level seen in fetal arterial blood fed by placental gas exchange. Values near the adult range (90–100%) aren’t expected in the fetus, and very low saturations (20–40%) would indicate significant hypoxemia. Thus 40–70% best represents normal fetal SpO2.

In utero, oxygen delivery to the fetus occurs through the placenta, and fetal hemoglobin binds oxygen with higher affinity, so arterial oxygen saturation is lower than after birth. The normal fetal oxygen saturation range is about 40–70%, reflecting the typical level seen in fetal arterial blood fed by placental gas exchange. Values near the adult range (90–100%) aren’t expected in the fetus, and very low saturations (20–40%) would indicate significant hypoxemia. Thus 40–70% best represents normal fetal SpO2.