Not sure but I imagine its any contact between the cervix and prodtaglandins in the semen that counts.
But presumably if baby is nearly baked your cervix would be quite low anyway increasing chances of the 2 being in contact?
Whatever you do just have fun!
I'm starting to think there is something wrong with me as I am totally not at that 'get the baby out of me' stage yet. I keep getting periods of being shattered mixed with the uncontrollable urge to clean and I have hip/back pain but I'm generally pretty well.
Perhaps its because I am almost aiming for the date 2 weeks after my due date as the date when he will be here by???