What factor is least likely to interfere with fetal heart rate monitoring?

Natural maternal breathing is the factor least likely to interfere with fetal heart rate monitoring because it is a normal physiological process that does not significantly impact the transmission of fetal heart sounds or the monitoring equipment. Fetal heart rate monitors are designed to detect the fetal heart rate through the quiet, rhythmic sounds generated by the heart, and maternal breathing generally occurs at a frequency and intensity that does not disrupt this detection.

In contrast, maternal body position can significantly affect the position of the fetus, the amount of amniotic fluid, and the placement of the monitor, which can all influence the accuracy and clarity of heart rate readings. Uterine contractions create pressure that can alter blood flow and change the fetal heart rate pattern, complicating monitoring. Fetal movements can also cause temporary changes in heart rate readings, as the movement may influence the position of the fetal heart relative to the monitoring device. Therefore, while all factors can affect fetal heart rate monitoring to some extent, natural maternal breathing is the least likely to cause interference.