Embryonic and Fetal Development Lab

Fertilization

Week 1 Fetilization- The sperm and egg join also known as conception. (Not embryonic stage yet)

Week 2 The embryonic disk forms. Gastrulation

Week 3-Early formation of the central nervous system, backbone and spinal column has begun. Major organs are starting to develop.  

          Week 5-heart begins to beat. The brain has developed into 5 areas and some cranial nerves are visible.             Arm and leg buds are visible and the formation of the eyes, lips, and nose has begun. The spinal cord                 grows.The placenta begins to provide nourishment for the embryo.

Week 7

Week 7-Major organs have all begun to form. The embryo has developed its own blood type, unique from the mother’s. Hair follicles and nipples form and knees and elbows are visible. Facial features are also observable. The eyes have a retina and lens. The major muscle system is developed and the embryo is able to move.

Week 8- The embryo is reactive to its environment inside the amniotic sac where it swims and moves. Hands and feet can be seen. At the end of week 8, the embryonic period is over and the fetal stage begins.

Week 13-16

The brain is fully developed and the fetus can suck, swallow, and make irregular breathing sounds. Eyebrows and eyelashes appear and the fetus makes active movements including kicks and even some somersaults.

Week 20-“Quickening” (when the mother can feel the fetus moving) usually occurs around this time. Finger and toenails appear. Lanugo, a fine hair now covers the entire body. The fetus can hear and recognize the mother’s voice. Sex organs are visible on ultrasound devices.

week 25-28

Rapid brain development occurs during this period and the nervous system is able to control some bodily functions. The fetus’ eyelids now open and close. At 25 weeks there is a 60% chance of survival if born. The fetus is considered legally viable at 28 weeks and there is a 90% chance of survival if born at this point.

Term Pregnancy

Week 36-37 

Most babies will be in a head down position at this point. However, about 4% of the babies will be breech.

Pregnancy is considered a "term" pregnancy at this point and nothing will be done to stop labor in most circumstances. You should plan to take a tour of your birth facility if you have not previously. If you are having a home birth try to invite everyone over for a quick run through of what you expect.