Best definition
womb baby
n. 1. Affectionate term for a baby carried in the mother’s womb prior to birth. Alt.: wombbaby. syn.: womb

child, wombchild; Antonym: embryo, fetus: (dispassionate/clinical references to babies prior to birth.)

The pregnant mother’s dreams for her womb baby compelled her to plan for the nursery. (versus, The scan revealed a viable fetus.)
womb baby: define #2
womb baby
A baby or small child that is so cute or pleasant that being around them makes you wish for a child of your own.
“The kid I babysit for is so sweet and well-behaved. He is such a womb baby!”