I may be partly responsible, I trained as documentary photographer at uni, after having pfb,
I did do several pregnancy/ birth projects, after the first ,I had quite a few requests, after other parents saw peoples books, and I know that other people did carry on theme, it's being going on for years,
it wasn't about having pretty portraits, It was just creating a visual story, so a lot of the portraits are graphic, but put together gives a good timeline.
I only work with people who are interested in the documentary aspect.