The stages of fetal development

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 mother’s.

Week 3: By the end of the third week the child’s backbone spinal column and nervous system are forming. The liver, kidneys and intestines begin to take shape.