I have not spoken to anyone in RL about this, but before DS (dc2), while in the bath, I had a go to see if I could feel whether my cervix was starting to dilate. It freaked me out when I could quite clearly feel his head! It was very hard, and I could feel quite a bit of it - maybe 4cm or so. No wonder it felt like he was about to drop out!
Has anyone else done this, and is it usual to be that dilated and not be in labour - he arrived about 3 days later? My waters were intact at the time (they went with a huge gush during labour), and I was surprised his head was not more 'cushioned', and I could feel it so clearly.
Disclaimer - I am not advocating doing this btw, as I am sure it must increase risk of infection etc etc