North American Registry of Midwives (NARM) Practice Exam

In the case of an occiput-anterior delivery, how does the birth of the head occur?

1. Flexion

2. Extension

3. Flexion then extension

4. Extension then flexion

The correct answer is: Extension

In an occiput-anterior delivery, the birth of the head typically occurs through a sequence that culminates in extension. During labor, as the head descends into the pelvic inlet, it rotates into an optimal position for birth, which is the occiput anterior position. When the crowning occurs, the vertex of the fetal head reaches the vaginal introitus, and as the head continues to descend, it begins to extend. The chin moves away from the chest, allowing the occiput to slip under the pubic symphysis. This extension is critical as it facilitates the emergence of the forehead, face, and chin after the occiput has cleared the pubic bone. While flexion is essential earlier in the process for the fetal head to navigate through the birth canal effectively, it is the act of extension during crowning that allows for the complete delivery of the head in an occiput-anterior position. Consequently, recognizing that the delivery phase specifically involves this extension provides clarity in the uncomplicated mechanics of an occiput-anterior delivery.