Is it a baby or a watermelon? A charming board book perfect for any curious toddler welcoming a new sibling What’s growing in Mommy’s tummy? Every month it grows bigger, from the size of a poppy seed to a peach, from avocado to mango to watermelon! Watch Mommy’s tummy grow in this sweet little book, perfect for mothers-to-be and soon-to-be big siblings.