From the Guidelines
A normal fetal heart rate is between 110 to 160 bpm.
Fetal Heart Rate Classification
The National Institute of Child Health and Human Development (NICHD) categorizes fetal heart rate tracings into three categories:
- Category I: Normal, which includes a normal baseline fetal heart rate (FHR) of 110 to 160 bpm, moderate baseline FHR variability, and the absence of late or variable decelerations 1.
- Category II: Indeterminate, which includes FHR tracings that do not meet the criteria for Category I or III, such as bradycardia (< 110 bpm) or tachycardia (> 160 bpm) 1.
- Category III: Abnormal, which includes FHR tracings with absent baseline variability and recurrent decelerations, and/or bradycardia 1.
Postnatal Heart Rate
After birth, a normal heart rate for a term newborn is between 100 to 190 beats per minute when awake, and as low as 70 beats per minute while sleeping quietly, without signs of circulatory compromise 1.
Key Points
- A normal fetal heart rate is between 110 to 160 bpm 1.
- The NICHD categorizes fetal heart rate tracings into three categories: Normal, Indeterminate, and Abnormal 1.
- Postnatal heart rate ranges for term newborns are between 100 to 190 beats per minute when awake, and as low as 70 beats per minute while sleeping quietly 1.
From the Research
Normal Fetal Heart Rate
- The normal fetal heart rate is generally considered to be between 110 and 160 beats per minute (bpm) 2, 3, 4, 5.
- However, some studies suggest that the normal range may be narrower, between 120 and 160 bpm 2.
- Fetal heart rate can decrease slightly during gestation 2.
- A fetal heart rate above 160 bpm is considered tachycardia, while a rate below 110 bpm is considered bradycardia 4, 5.
Factors Affecting Fetal Heart Rate
- Gestational age can affect fetal heart rate, with higher heart rates associated with earlier gestational ages 6.
- Fetal heart rate can also be affected by labor, with some studies suggesting that a heart rate between 150 and 160 bpm during labor may be associated with a higher incidence of labor complications 3.
Diagnosis and Interpretation of Fetal Heart Rate
- Continuous fetal heart rate monitoring is widely used during labor to detect potential fetal distress 5.
- Abnormal fetal heart rate patterns, such as recurrent late or variable decelerations, can be predictive of severe fetal acidosis 5.
- Electronic fetal monitoring can have a high false positive rate, leading to increased operative deliveries 5.