It's the mystery of mysteries-what's going on inside a pregnant woman's belly? That's what Jennifer Davis's older children wanted to know while she was expecting the younger. So to explain, she wrote BEFORE YOU WERE BORN, now with 102,000 copies in print, a joyful lift-the-flap book that tells the parallel story of mother and baby during the nine months of pregnancy.<P> Illustrated with full-color whimsy by Laura Cornell, whose delightful work is familiar to readers of Jamie Lee Curtis's Tell Me Again About the Night I Was Born and When I Was Little, BEFORE YOU WERE BORN is a month-by-month countdown written in rhyming verse.<P> Each page shows what's happening to the mother on the outside and then, under the flap, in the mother's belly to the baby on the inside. Children learn how Mommy is feeling and how the baby is developing, about hiccups, kicks, and umbilical cords, a first heartbeat, and the contractions that mark the beginning of labor.<P> For expectant mothers and curious little kids, and especially for kids with siblings on the way, it is an interactive storybook that delivers delight and information and reassurance, too. <P>