http://beautifulcervix.com/about/

“My intention with this project was to better understand my cycle and the changes in my cervix throughout the month.  As a doula and student midwife, I used this project to help me see how a cervix might look different throughout the cycle in the absence of vaginal infections and to understand speculum exams.  You may notice on the right side of some photos, some jagged looking skin, which is the remnants of my hymenal ring.  My os (opening to the cervix) is round because I have never given birth; the os becomes more of a slit after childbirth.”

Apparently, if you have a baby, the opening to your cervix will never be round again.  [Also, re:  this website, WTF?]