Empathy at a tender age

The other day Ben, Caitlin, and I were driving in the car. Somehow Ben and I got on the topic of babies and where they come from. It's come up before, but he was much more curious this time and asking more direct questions. Eventually we got to this...

Ben: How does the baby get out? Through a hole in in the tummy?
Me [being as honest as I can without too much detail]: Sometimes, yes, but usually the baby comes out through the vagina.
Ben: [silent and thinking]
Me [assuming he's wondering how on earth that works]: And it hurts, because a baby's big, and well, a vagina's small, but women's bodies are designed to do this, so it doesn't hurt for long.
Ben [a little more silence, then]: I wouldn't like that if I was a woman.