What factor does NOT contribute to fetal heart rate variations during labor?

Fetal heart rate variations during labor are influenced by several factors that can trigger sympathetic or parasympathetic responses or impact uteroplacental blood flow. Among the provided options, maternal sleep does not contribute to fetal heart rate variations during labor.

During labor, the physiological stress and changes experienced by the mother—such as contractions and exertion—are the primary contributors to fetal heart rate variability. Crying and feeding can induce changes in maternal heart rate, blood pressure, and hormone levels, affecting uterine and placental perfusion, thereby influencing the fetal heart rate. Exercise leads to increased maternal heart rate and oxygen demands, which can similarly affect fetal status in labor.

In contrast, maternal sleep is generally a state of rest where the mother’s body is in a relaxed state, and uterine contractions are minimized. This lack of active engagement does not elicit the same cardiovascular and hormonal responses as other activities do during labor, resulting in stable fetal heart rate patterns that are not influenced by variations in activity or stress levels associated with the labor process.