At the end of 13th week of pregnancy the future baby weighs about 20-30, its growth is 9-10 cm., and the head diameter of approximately 2.5-3 cm. Most of the time a baby is floating in the amniotic waters in the dream, but when it is awake, then using ultrasound we can see how its hands compress into fists, how it is sucking a finger or shudders.
Its skeletal system is actively formed: bones of the arms and legs are lengthening, first ribs are formed, begins the process of ossification of the spine and skull. By that time there are all the calf’s teeth laid, the prints appeared on the fingers, the pancreas produces the first insulin.
Future baby’s head is no longer pressed to its chest, facial features are clearly distinguished on its face, chin, nose, ears located at the sides of the head, eyes are almost in their seats, however, they still are closed tightly with conjoined eyelids.
The thyroid gland of a baby is already sufficiently developed and systematic breathing is well formed too.
The child breathes, training the muscles of the diaphragm and chest, its glottis is closed tightly. Sexual differentiation: the boy begins to develop the prostate gland and genital tubercle elongates into the penis, the ovaries placed in the abdominal cavity of a girl descend into the pelvis and genital tubercle bends down – because it will form the clitoris.
The skin of a baby is still very delicate and thin, the skin is red and wrinkled, on the surface there are small blood vessels. It is due to the fact that the baby has not a layer of subcutaneous adipose tissue yet.