As the obituary of Allan Ahlberg observed, The Baby’s Catalogue, written by him and illustrated by his wife, Janet, was based on the fact that babies like to spot other babies. However, this one was far more creative than other books showing babies.
Allan told a conference that I went to as a children’s librarian that he and Janet, both bookish, were not best pleased that their toddler Jessica’s favourite book was the Mothercare catalogue. Janet therefore included things that babies would recognise: a teddy, a highchair, a swing.
I am retired now, but in talking to parents about sharing books with very young children, I recommended The Baby’s Catalogue as a very useful start.