What type of deceleration occurs when the fetal heart rate drops as a result of umbilical cord compression?

Variable deceleration is characterized by a sudden drop in fetal heart rate that is related to umbilical cord compression. This type of deceleration is often seen during labor and can occur with changes in the mother's position or contractions. The decline and subsequent recovery of the fetal heart rate is typically abrupt, and the timing of the deceleration may vary with each uterine contraction.

The mechanism behind variable decelerations involves the pressure exerted on the umbilical cord, which reduces blood flow and oxygen delivery to the fetus, leading to a transient decrease in heart rate. This is important for clinicians to recognize, as it can indicate a compromised situation for the fetus, necessitating careful monitoring and possible interventions to relieve cord compression.

The other types of decelerations have distinct characteristics: early decelerations occur in conjunction with contractions and are typically gradual, reflecting fetal head compression. Late decelerations happen after a contraction ends and indicate uteroplacental insufficiency, resulting in a delayed response in the heart rate. Prolonged decelerations are defined as a decrease in heart rate lasting longer than 2 minutes but less than 10 minutes, often due to various stressors like uterine hyperstimulation or fetal acidemia. Each of these