What is the definition of fetal heart rate variability?

Fetal heart rate variability refers to the fluctuations in the fetal heart rate that occur over time. It is a key indicator of the autonomic nervous system's regulation of the heart and is crucial in assessing fetal well-being. Healthy variability signifies a responsive and well-oxygenated fetus, while reduced variability can indicate potential distress or other issues, such as hypoxia.

It is important to differentiate this concept from the average heart rate of the fetus, which measures a single, static number rather than the dynamic changes that occur. Similarly, fetal heart rate during contractions specifically refers to heart rate changes occurring in response to uterine contractions, rather than the broader pattern of variability. The heart rate response after birth pertains to newborn stabilization rather than the in-utero assessment essential for monitoring fetal conditions. Thus, fluctuations in fetal heart rate captures the critical essence of fetal heart rate variability as an essential marker for assessing fetal health.