The phrase "complete dilation" refers to a medical term that means the opening or widening of a body part, usually a blood vessel or the cervix. It signifies that the body part has reached its maximum or fullest size. Full definition
You may also feel your baby moving down as your cervix nears complete dilation. (verywellfamily.com)
Once a Mother achieves complete dilation she is usually encouraged to begin to push out her baby. (thematrona.com)
This works beautifully with firsts too but second labors are so much smoother that frequently, a little time in the tub is all the pain management needed before complete dilation. (mom.me)