10-3. FETAL ADAPTATIONS (OR THE MECHANISM OF LABOR)
a. Cardinal Movements. This refers to the movements made by the fetus
during the first and second stage of labor. As the force of the uterine contractions
stimulates effacement and dilatation of the cervix, the fetus moves toward the cervix.
When the presenting part reaches the pelvic bones, it must make adjustments to pass
through the pelvis and down the birth canal (see figure 10-6).
C--Internal rotation to OA.
Figure 10-6. The mechanism of labor in the left occiput anterior (LOA) presentation.