A friend of ours had a dog who had puppies right about the time my wife got pregnant with my youngest. So they were somewhat familiar with babies. We told them they had a baby sister in mommy's tummy. We said mommy would go to the doctor when the baby was big enough and then the baby would come out. I thought that explanation might start a lot of questions but it didn't. They seemed satisfied with that. I've found most of the time when small children ask a question, they want an inch not a mile.
he must be a nice child for he didn't ask how the baby got in mummies tummy?