Will You Carry Me?, by Helen van Rossum, illustrated by Peter van Harmelen, Kane/Miller Publishing, 2005.
I bought this book about ten years ago -- before I became a mommy, or even knew that I was becoming a mommy -- because I saw the artwork featured in an exhibition of children's book illustrations. I wasn't disappointed in the story then; in fact, I donated the book to the library where I was working as a children's librarian. Fast-forward ten years, and my own son picked this book out (on his own) from another library. And it is still good.