The second book I got my son (and actually his least favourite) is 'Our Water Baby' by Amy Maclean and Jan Nesbitt.
This is probably his least favourite because of the pictures. I am not too fussed about the pictures either to be honest.
However, it is, so far, the only home 'water birth' book I have found and it does cover a few things I might not have thought of that a child might worry about if you are planning a water birth. Such as how the baby will not have to 'swim' in the water and that the baby 'holds its breath' until it is lifted up out of the water. My son loves going to the pool, but he certainly does not 'swim' yet and hates having water on his face - so he might be worried about the baby being born in the water. This books covers home water births wonderfully I think. But the pictures are a bit messy in a childish way (so not sure how much a child would take in ...'yes mum I see the lady in the pool with the baby but look at all these fun colourful drawings of puppies and frogs around the page!' - despite they do cover the normal noises mummy might make and how she will feel better making them and feel even more better when the baby is born, especially in the soothing birthing pool).
The pictures are also not very graphic (some people might like this?). Which I actually think is not always the best of things. But I guess a child might not see much if you are in the water anyhow. However, I think because your child might see something, it is good for them to see such pictures so they are reassured that it is completely normal and what its supposed to look like (which is why I like the next book I am about to post about!)! hehe