Although many women have only just recently discovered their pregnancy at eight weeks' gestation, the fetus has already made several changes from the cluster of cells that appeared shortly after conception. Weight, length, body characteristics and facial features are all developing on the outside, while small and delicate organs are forming on the inside. Although an 8-week-old fetus may not show much detail on an ultrasound screen, there may be a visible heartbeat that resembles a tiny blinking light.
Size
At 8 weeks, a fetus is growing at the speed of about a millimeter a day. However, this growth is not just in height. Growth spurts are taking place all over the body as the fetus gains weight and as the arm and leg buds grow in size. At this stage, a fetus is about the size of a raspberry or kidney bean, and is measured from crown to rump on an ultrasound.
Organs
The fetal heartbeat is beating at a rate of approximately 150 times per minute, which is about twice as fast as the mother's heartbeat. The breathing tubes that go from the throat to the lungs are beginning to form, and nerve cells in the brain are developing rapidly. The gender of the baby will not be visible for quite some time, however, because the genitals have not yet developed.
Face
An 8-week-old fetus is beginning to resemble a baby, especially since some distinct characteristics are forming on the face. The eyelids, although very thin, are formed, and the lips and nose are beginning to develop. More specifically, the upper lip and the tip of the nose are prominent at this time. All of these characteristics are forming on a head that is oversized during this stage. At this point, the head makes up about half of the fetus.
Body
The body is quickly developing as arm and leg buds grow into limbs. The back is also developing and is more visible now. The webbing between the fetus' fingers and toes is beginning to disappear. At this stage, the fetus may begin to make sudden jerking movements, although the mother will not be able to feel any movement for approximately 10 more weeks.
Surroundings
Amniotic fluid, which surrounds the fetus and provides protection and cushion, is increasing at a rate of about 2 tbsp. per week in order to accommodate the growing fetus. The umbilical cord is growing longer as well. The yolk sac, which is visible on an ultrasound at this stage, is still present to provide nutrients to the fetus while the placenta continues to develop.
