How does fetal cardiac output (CO) differ from that of adults?

Fetal cardiac output (CO) differs from that of adults in several significant ways, and the statement that the stroke volume does not fluctuate aligns with the unique physiology of fetal circulation. In the fetus, cardiac output is determined primarily by heart rate and stroke volume, but unlike adults, where stroke volume can vary due to physical activity or other factors, fetal stroke volume remains relatively stable.

This stability is crucial because the fetal circulatory system is designed to prioritize blood flow to vital organs such as the brain and heart, thereby maintaining a consistent and adequate supply of oxygen and nutrients. The fetal heart rate is typically higher than that of an adult, typically ranging from 120 to 160 beats per minute, which contributes to a sufficient cardiac output despite the relatively limited variation in stroke volume.

Understanding this distinction helps in monitoring fetal health during pregnancy and labor, as fluctuations in heart rate or any significant changes in blood flow could indicate potential fetal distress or compromise.