Normal values indicate that the fetus is not in distress by showing a fetal heart rate between 120 and 160 beats per minute. A variability of 5 - 25 beats per minute from the baseline (normal) fetal heart rate may occur.

The fetal heart rate may drop slightly during a contraction, since placental blood supply is diminished under the compression of a uterine contraction. This is normal as long as the fetal heart rate recovers quickly once the contraction has stopped.

Fetal heart monitoring tests can detect the following abnormal situations or conditions:

• Cord compression (there is no free blood flow to the fetus)
• Fetal heart block (where there is a block of electrical flow within the heart muscle causing an altered heart rhythm)
• Fetal malposition
• Fetal hypoxia (insufficient oxygen supply to the fetus)
• Infection (monitoring cannot diagnose an infection, but can suggest the presence of an infection)
• Uteroplacental insufficiency (insufficient oxygen exchange between the uterus and the placenta)
• Fetal distress
• Abruptio placenta