Canadian Practical Nurse Registration Examination (CPNRE) 2026 – 400 Free Practice Questions to Pass the Exam

During labor, primary powers refer specifically to the physiological forces that are responsible for the progression of labor. Contractions are the rhythmic tightening and relaxing of the uterine muscles, which play a critical role in dilating the cervix and pushing the fetus down the birth canal. These contractions are essential for the labor process, as they facilitate the descent of the fetus and are the driving force behind cervical effacement and dilation.

Emotional support is important for the laboring person but does not constitute a primary power. Similarly, maternal pushing efforts come into play during the second stage of labor and are considered secondary powers, as they assist but do not initiate or sustain labor by themselves. The position of the fetus, while relevant to the labor process, is not classified as a power but rather as a factor that can influence labor dynamics. Therefore, contractions are precisely what define the primary powers during labor.