Baby's First Ultrasound at 4 Weeks

This week marks the beginning of the embryonic period. From now until ten weeks, all of my baby's organs will begin to develop and function. As a result, this is the time when he/she'll be the most vulnerable to anything that might interfere with her/his development. Right now my baby-to-be is an embryo consisting of two layers: the epiblast and the hypoblast, from which all her/his organs and body parts will develop. The primitive placenta is also made up of two layers at this point. Its cells are tunneling into the lining of my uterus, creating spaces for my blood to flow into so that the developed placenta can provide nutrients and oxygen to my growing baby when it starts to function at the end of this week.Also present now are the amniotic sac that will house my baby, the amniotic fluid that will cushion her/his as she/he grows, and the yolk sac that produces my baby's red blood cells and helps deliver nutrients to her/his until the placenta is ready to take over this duty.

(Source: Babycenter)