4 weeks 6 days

This is what is on my Fertitlity friend for this week...

Implantation is complete. Your future baby has now reached beneath the lining of your uterus and growth is rapid. Your baby is now called an embryo. The embryo is still about 0.05 inches (1.25mm) long. It is deeply embedded in your uterus.

It is now possible to identify the fold of skin that will become your baby's head. A heart forming plate has developed and the central nervous system, muscles and bone are in the early stages of development. Your baby's heart has started beating. The brain, spine and beginnings of the nervous system are forming.

By the end of this month, your baby will resemble a tiny tadpole, barely the size of a grain of rice. A distinct organization, however, is becoming visible. There is a stripe down the back of the embryo which is curling over to form a groove which will seal up to form the neural tube. This will turn into the spinal cord and brain. The top of the tube is flattening out and expanding to form the front part of the brain.

The placenta, which will provide nourishment to your developing baby later in your pregnancy, is not yet formed. Right now your baby is nourished from you via hundreds of tiny "roots" that cover the amniotic sac. The nourishment is channeled from you to your baby from these roots through a stalk that will become the umbilical cord. The placenta will begin its development this week. It will form in the site that the fertilized egg attached to the lining of your uterus at the time of implantation. A bulge is developing where your baby's heart will be and the blood vessels are growing into place.