Being pregnant is an exciting, life-changing event. There is much to worry over and even more to wonder about. At six weeks, your tummy is not yet protruding, but the fetus inside is growing rapidly. Although it is only four weeks after conception, the blood is already flowing inside the tiny fetus. With each passing day, it will more and more resemble the infant that you will give birth to.
Size and Weight
According to the Mayo Clinic website, by the end of the sixth week, your baby is estimated to be 1/6 to 1/4 inch in length. The fetus is about the size of a lentil bean, and it weighs less than a gram.
Head
BabyCenter.com explains that the basic features of the face begin to appear at six weeks. The nose, jaw and palate are beginning to form. There are dark spots where the eyes and nose are developing. Small indentations on each side of the oversize head mark where the ears are going to be. The optic lenses and vesicles of the eyes develop. The nostrils also form and shift into the correct place on the face.
Heart and Blood
ParentsConnect says the earliest form of a heart is visible at six weeks. The heart beats regularly, but is still too quiet to hear. Its rate is around 100 to 160 beats per minute, almost twice as fast as an adult's heart. Blood is beginning to flow through the underdeveloped circulatory system. The heart and circulatory system form in the center of a group of cells called the mesoderm. This layer is also the foundation for the bones, kidneys, muscles and some of the reproductive system.
Organs
By 6 weeks old, a fetus's brain is forming. The cerebral hemispheres are becoming larger. BabyCenter says that the intestines are growing, although they are actually found outside the body inside the umbilical cord. The primary loop of the intestine is visible. The pancreas is already ready to handle digestive enzymes and insulin. The budding tissue of the lungs, liver and thyroid glands are beginning to appear.
Arms and Legs
As ParentsConnect explains, the arms and legs are just tiny buds that are beginning to form. They resemble very small flippers. At the ends of the arms and legs are little webbed objects that will turn into the fingers and toes. Although their appearance will drastically change in the coming months, the arms and legs are easily recognized. During this week, the body begins to straighten slightly as the leg buds recede into their proper place.
