Many years ago I took a psychology course and I recall the professor chatting about childrens memories. I remember he said that around the age of 2-3 children are able to recall their births, but eventually may loose the actual memory, replaced by stories or images of it. I did a quick google search on the subject and came up with this:
Interestingly enough YDD (4) and I were playing 'house' just the other day. She wanted to be the baby inside my uterus and wanted me to call the midwives. I said "Ok, I'm pushing now" and she said "no, you aren't pushing, I'm pushing myself out, with my feet, I have to get out of there and into the water and you are taking too long so I did it myself".
Interestingly enough this is pretty much exactly what happened. I was in labor for 20 hours, I pushed for only 6 minutes and during that time the midwives were unable to detect a heartbeat and were saying "we have to the baby out now!". With my first DC the pushing phase was relaxing and controlled, with YDD I was not pushing at all and I yelled at everyone not to touch me because it felt like they were pulling her out, yet they weren't touching me at all. I would describe it as she was pushing herself out....
That said it's plausable DD has heard me talk about her birth, though I know I have not described to her in such a way, I may have chatted with someone else about it within ear shot of her, thus affecting her memory of the event.
I'm intrigued by the discussion of young gifted children and their memories in comparison to the general populace and am off to do more research.