Anti-Abortion Prolife Video: Development of the Unborn Baby. Anti-Abortion Prolife Video: Development of the Unborn Baby. Fetal Development; From conception to birth; Day 1: fertilization: all human chromosomes are present; unique human life begins. Day 6: embryo begins implantation in the uterus. Day 22: heart begins to beat with the child's own blood, often a different type than the mothers'....