Day 1 : Fertilization occurs.

Day 6 : Embryo implants in the uterus.

Day 18 : Human heartbeat can be detected.

Day 21 : Foundations for many organs are apparent.

Day 31 : Human anatomy ( arms, legs, etc. ) develops.

Day 38 : Every muscle block is present; baby begins moving independently.

Day 40 : Brain waves can be detected.

6 Weeks : EKG and EEG can be done; little fingers and little toes are forming.

8 Weeks : Every organ system is present, the baby is swimming in amniotic fluid.

12 Weeks : The Baby has sleep/wake cycle, digests food, swallows, excretes, breathes amniotic fluid, has vocal cords, and cries.