A nurse is assisting in the care of a client who is in active labor. The nurse notes variable decelerations of the FHR. The nurse should identify which of the following as a cause of variable decelerations?

Choice A rationale Variable decelerations are characterized by an abrupt decrease in the fetal heart rate, often V, W, or U-shaped, and are primarily caused by umbilical cord compression. This compression reduces blood flow and oxygen transfer to the fetus, leading to a transient hypoxic event and subsequent FHR deceleration. Choice B rationale Maternal fever typically causes fetal tachycardia, an elevated baseline fetal heart rate (above 160 beats per minute), due to increased fetal metabolic demands and a direct effect of elevated maternal temperature on fetal physiology. It does not directly cause variable decelerations. Choice C rationale Fetal head compression typically causes early decelerations, which are symmetrical, gradual decreases in FHR that mirror uterine contractions. This occurs due to increased intracranial pressure stimulating the vagus nerve, leading to a transient slowing of the heart rate. Choice D rationale Polyhydramnios, an excessive amount of amniotic fluid, is generally associated with conditions like maternal diabetes or fetal anomalies. While it can alter uterine distension, it is not a direct or primary cause of variable decelerations, which are specifically linked to cord compression.