D.T.
My daughter was 6 too. I got on YouTube, watched a few videos and showed the appropriate ones to my daughter. Not many though, usually the ones of the baby moving in the tummy. She loved watching and feeling mine. We looked at development pictures, you know, the ones that show what the baby looks like at each stage and how big it is compared to something everyday. There are also tame anatomy images out there of the female body, you can show her the uterus and whatever else you are comfortable with showing her.
My daughter had a basic knowledge for the female body before I got pregnant. She's had a few times where she's been "ouchie" down there and I've had to put medicine on her. This led to questions and requests from her to not "tickle" her "bump". She wanted to see her "lady bits" one time so we got out a mirror. She'd also been in the bathroom with me one day during "that time of the month" and had questions. So those lead to the whole conversation about how all women have a special place inside their bodies (she did too) that babies grow in. I told her that in order for a baby to grown healthy it needed a special "nest" of blood, that an adult woman's body makes the "nest" every month inside that special place. If there was no baby the woman's body would get rid of the old "nest" and makes a new one. That when she was older her body would begin making "nests" too and that she needed to come tell me if and when it happens. She wanted to know where the "nest" came out of so the mirror came out again and I was able to show her on her own body her vagina and explained that that was where the blood came from, that it lead to the "special baby place" inside and that it was the natural way that babies are born. She also got a little worried about how tiny she was, but I told her that she was tiny because she was still a little girl and not a full grown woman. She would grown everywhere in time and when she's an adult her body will be ready. When I was pregnant she asked about the brith and I had to tell her that for me I would need a doctor's help when it was time for "Pindot" to be born. That lead to another conversation later on.