North American Registry of Midwives (NARM) Practice Exam

What physiological response may occur as a result of head compression during labor?

1. Fetal heart rate elevation

2. Fetal vagal nerve response

3. Increased maternal stress

4. Decreased uterine contractions

The correct answer is: Fetal vagal nerve response

During labor, head compression occurs when the fetal head exerts pressure against the cervix and pelvic structures. This pressure can stimulate the baby’s vagus nerve, which is part of the autonomic nervous system responsible for regulating bodily functions including heart rate. The stimulation of the vagus nerve results in a fetal vagal nerve response, causing a transient decrease in fetal heart rate, known as a variable deceleration. Understanding this physiological response is crucial for midwives and healthcare providers, as it can indicate normal fetal adaptation during contractions, reflecting the interplay between labor dynamics and fetal well-being. When assessing fetal heart patterns during labor, recognizing that head compression leads to a vagal response helps differentiate between benign variations related to labor progress and more concerning patterns that might indicate distress. Other physiological responses, such as increased fetal heart rate or maternal stress, do not typically result directly from head compression. Additionally, decreased uterine contractions are not a response to head compression; rather, they are often related to different factors such as uterine fatigue or lack of labor progress. Therefore, the vagal nerve response is the most accurate physiological response to consider in this context.