When do most women start dilating in their pregnancy and their mucus plug comes out

Cervical dilation: Depends. If you have had one or more children vaginally before, you may be a little dilated at your baseline. Most women will not dilate their cervix until in labor. Definition of labor is adequate uterine contractions that cause cervical dilation and effacement (thinning out of the cervix). Mucous plug usually comes out late in pregnancy (after 36th week or so), but again, can happen sooner.