This is a board book for the very young,complete with a button to press which produces a baby's giggle! Nicely simple sentences with easily understood information, the story includes grandma's coming to stay while mum is in hospital, baby arriving home with mum and dad (no sex given - a real strength of this book), Polly's excitement at meeting the baby, helping mum with the baby, Polly's wondering why the baby cries, Polly and mum reading a story while the baby breastfeeds, lots of visitors coming to meet the baby, taking the baby to the park for the first time, and playing with mum and dad while the baby sleeps. The emphasis is on the big sister and all the things she can do that the new baby can't, and Polly is very happy being a big sister. There is a book for boys too: I'm a New Big Brother (Pirate Pete series, ISBN 9781409313748), which I have not seen but will be a very similar format.