We've got "So that's where I came from". Describes different types of families, different types of conception (including a page or two on IVF and a paragraph or two on using donor gametes), different types of birth, etc. Basically it emphasises that one way isn't the "right" way, but that there are many paths to making a family. I like that it doesn't make the less common paths "special".
It's aimed at a primary school age group, about ages 7-12, but my sister used simpler language plus the pictures to tell her son about his conception and birth whenever I had an IVF appointment of my own. When my nephew was 3 or 4 his favourite page was either the one with the cartoon picture of a woman at embryo transfer or the doctor/scientist picture - possibly because they're the pages he saw most often when my sister was telling him what his aunty had been doing today.