With regard to primary and secondary powers, the maternity nurse should know that:

Primary powers are responsible for effacement and dilation of the cervix.

Scarring of the cervix caused by a previous infection or surgery may make the delivery a bit more painful, but it should not slow or inhibit dilation.

Pushing in the second stage of labor is more effective if the woman can hold her breath to control some of her involuntary need to push, as the nurse directs.

Effacement generally is well ahead of dilation in women giving birth for the first time; they are more together in subsequent pregnancies.