Answer:
The commencement of contractions signifies the start of the primary fundamental action of labor. In this phase, the cervix, which is the inferior portion of the uterus, initiates the process of effacement and dilation. Effacement pertains to the reduction of thickness of the cervix, whereas dilation refers to its expansion. The contractions play a crucial role in making the cervix supple and slim, while also making way for the baby's passage through the birth canal.