I have answered this question before. At least I think I have. I do recall my four year old (now 13) asking me about the body. I don't recall the exact way he phrased it anymore. He also wanted only specific answers. If you went further than what he wanted to know, he would tell you that he got the answer he wanted and went on his merry way.
This morning after the preschooler and toddler fought over the baby, E looked at me with that gorgeous, innocent face of his and asked me how the "doctor got L out of your stomach". Well now. How do I answer that one? Do I traumatize him for life and show him one of the many you tube videos on women in excruciating pain giving child birth? Do I go to the library like I did with my eldest (we didn't have a computer never mind the internet then). Or do I find something in between online. How much does he need to know? Will he truly understand or will he be more confused?
He will be 5 in about a week's time and I'm worrying about getting his gift done, starting on his decorations and designing his Zombie cake, I don't need to think about this too. Kid what are you thinking?!!! Can't we just go back to thinking about Zombie's and not worry about how your brother got here? At least until after your birthday party?