Just out of curiosity, when a women gives birth, is it only her cervix that dilates 10cm? Or the opening as well?
Well, Efface Paint, I assume that by “opening” you mean the vagina? Because the cervix IS an opening – the opening from the uterus into the vagina, to be precise.
The cervix, since it is made of tougher tissue that helps “hold the baby inside the uterus” during pregnancy, must go through dramatic physiologic/anatomic changes to gradually stretch to the 10cm “goal” to allow for delivery of the baby (especially the baby’s head, which is the widest and least-collapsible part).
The vagina, on the other hand, is perfectly designed to stretch quite a bit, regardless of pregnancy or not, so there’s no preparatory “physiologic dilation” that has to happen there. True, sometimes the delivering doctor might do an episiotomy (cutting the vaginal and perineal tissue) to “enlarge” the opening if they feel the baby is having trouble getting out, but more and more studies seem to show that episiotomies are used more than is truly necessary. With careful stretching by the physician (or the patient’s partner, midwife, etc) during the preparatory stages of labor, the vaginal tissues can accommodate a lot of tension without tearing or ripping (at least, not tearing too horribly). And TA-DA! Baby comes out!
(Now, when a mommy and a daddy love each other a lot… oh, but that’s a different story for a different time.) :)