What types of decelerations are categorized as early decelerations?

Early decelerations are characterized by gradual decreases in fetal heart rate that correspond with uterine contractions. This pattern typically arises due to head compression during labor. As the fetus's head descends into the birth canal, pressure is applied to the cervix and the pelvic walls, leading to a transient decrease in heart rate. The relationship between the deceleration and contraction is key; the deceleration begins with the onset of a contraction and returns to baseline as the contraction ends.

This distinct pattern of early decelerations is quite different from abrupt decreases that do not correlate with contractions, lengthy decreases that exceed 10 seconds, or sudden drops without any identifiable rhythm. Understanding early decelerations is critical for monitoring fetal well-being, as they generally indicate that the fetal heart rate response is physiological and means that the fetus is likely tolerating labor well.