During Week 6 of pregnancy, or 4 weeks after conception, the neural groove down the center of the embryo closes like a zipper, forming a tube that becomes the spinal cord and brain. The closing is faster toward the head end as the different parts of the brain develop. The ends of the groove then close. The heart now beats and pumps blood. Other organs and facial features are becoming more defined. Tiny buds appear that will become arms and legs. The embryo starts to take on the shape of a C; its skin is so thin, it is transparent. It is about an eighth of an inch long.
Did you know?
Your placenta is a multi-talented brand new organ that passes oxygen and nutrients from your blood stream to your growing baby. It also protects your baby from infection and helps to remove your baby's 'waste products', such as carbon dioxide. Linked to your baby by the umbilical cord, your placenta will weigh around 1.5lb by the time your baby is born.