Noun
baby-to-be (plural babies-to-be)
(informal) An embryo or fetus; an unborn child.
Pregnant women can also help their baby-to-be by selecting salmon—in one study, women who had a low fish intake were at an increased risk for preterm delivery and low birth weight. Source: Internet
Throughout your pregnancy, your baby-to-be was lulled to sleep by the motion you created when walking around. Source: Internet
So, she chose to wait at our store, browsed our children's section and even bought a book for her little baby-to-be! Source: Internet