In Utero is a Latin phrase meaning 'in the womb' and is used to refer to the period of time when a baby is developing in its mother's uterus. The term UNBORN refers to a fetus before it is born, while PREBORN refers to a fetus during the period of time before birth. Both terms are used to describe the same stage of development, but UNBORN is more commonly used to refer to the earlier stages of fetal development.