QCOM
Quillen College of Medicine, East Tennessee State University


Bradycardia

Baseline FHR less than 110 beats per min

(NICHD)

Fetal bradycardia is commonly associated with fetal hypoxemia. However, a number of causes must be considered:

  • Hypoxemia
  • Drugs
  • Maternal hypotension
  • Hypothermia
  • Maternal hypoglycemia
  • Fetal bradyarrhythmias
  • Complete heart block (Maternal SLE, CMV infection)
  • Congential heart block
  • Umbilical cord compression
  • Amniotic fluid embolism
  • Normal variation
As with fetal tachycardia, the bradycardic FHR must be analyzed for the presence of periodic changes and decreased variability. These findings are more consistent with hypoxemia. Some fetuses may display a bradycardic FHR but be completely normal. It should be remembered that the range of 110-160 does not represent all normal fetuses. The likelihood of a FHR in the range of 100-110 representing a normal variant increases as the fetus, and its nervous system, matures.

See illustration below for an example of bradycardia. Please click to enlarge.


 

Bradycardia Video 1

Bradycardia Video 2

 

 

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