Last summer (i.e. before we were expecting a baby) we checked out a book from the library because we liked the cover. It was called Too Small for Honey Cake. I ended up ordering it from Amazon because I adored the illustrations, but the story itself is cute too. It is told from the P.O.V. of Little Fox, who gets a little jealous when a new baby comes into the house. He gets jealous about having to share his old cradle and his father's attention, and gets annoyed that he has to be quiet when the baby is napping, etc. It's not a perfect story imo because Little Fox does say some pretty mean things about the baby, and acts out a little, but it's an honest look at a young child's emotions about sibling rivarly without judging or shaming them. Btw, there's no mom in the story, just a Daddy Fox... which was a little odd to me, but hey. It has a happy ending, naturally.
I think that book might come in handy to have on a shelf in case sibling rivalry rears its head (esp. with a three year old) but I wouldn't necessarily show the book to them FIRST while you were pregnant, i.e. putting the thought in their heads that the baby might be a problem. But if jealousy did happen in the first few days or weeks, it might be helpful to have on hand to help the kiddo process their emotions.
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