North American Registry of Midwives (NARM) Practice Exam

What is the characteristic of the lambda FHT pattern?

1. An acceleration followed by a quick deceleration with each contraction

2. An acceleration followed by a deceleration that occurs with each contraction

3. No changes in fetal heart rate

4. A predictable pattern associated with fetal malposition

The correct answer is: An acceleration followed by a deceleration that occurs with each contraction

The characteristic of the lambda fetal heart rate (FHT) pattern is marked by an acceleration followed by a deceleration that occurs with each contraction. This pattern indicates a physiological response of the fetus to the labor contractions, where the acceleration signifies a healthy fetal response, typically linked to adequate oxygenation and fetal well-being. Following this acceleration, the associated deceleration is reflective of the transient effects of uterine contractions, as they momentarily compress the umbilical cord or increase the pressure on the fetal head. Recognizing this pattern is important for midwives as it helps in evaluating fetal distress or well-being during labor. Specifically, this lambda pattern serves as a reassuring sign, indicating that the fetal heart rate is responding appropriately to the stresses of labor. In contrast, other choices describe variations or abnormalities in the fetal heart rate that do not apply to the classic lambda pattern, such as random decelerations not following contractions or describing patterns that suggest inadequate fetal positioning or distress, which would require different attention and evaluation strategies.