Books to explain pregnancy to 7 year old boy

[megsmeadow]

Just as the title really! Any recommendations for good books? We have two sons, one who is 7, and one who is 2.5. Our eldest has had very little body awareness until now and has started dropping in all the usual questions which I want to be honest but not pitch it too high level. He's quite concrete thinker and I think seeing things written and in pictures might help.
What did you do, what books have helped or just added to the confusion?
Thanks!!

 

[megsmeadow]

Haha, looks like I'm going it alone!!