Placental fetal blood flow abruptly passes into the bloodstream, similar to the blood circulation of an adult. With the first cry of the child and the beginning of the functioning of the respiratory system, a small circle of blood circulation is included.
The system of the great circle changes substantially: the umbilical vessels are emptied, the blood flow in the Aranzievi Strait connecting the umbilical and inferior vena cava stops, the connection between the atria disappears, the arterial (botallic) duct is emptied.
Hemopoiesis occurs in the red bone marrow, liver, spleen. The blood of the newborn hemoglobin and red blood cells is more than in an adult. This compensates for hypoxemia, which occurs during childbirth. The hemoglobin content is from 180 to 230 g /l, the color index is higher than one. Many newborns in the first two days have hyperleukocytosis 20x109 /l, leukocytosis gradually decreases to 10-12 days of life and is 10-12x109 /l.
The rate of erythrocyte sedimentation in newborns is slowed down and does not exceed 2 mm /hour. The blood of the newborn is richer in calcium salts than the maternal, the serum contains more albumins and g-globulins, and the sugar content is reduced to 044 g /l.
The heart of a newborn has a number of characteristics. It has a rounded shape, the atria have a larger volume relative to the ventricles. On average, the heart rate is 140 beats per minute, although in the first 24 hours it can drop to 110 beats per minute. The duration of the systole of the ventricles (024 s) is somewhat greater than the diastolic (021 s). Despite the fact that the shock volume of blood is relatively small (3-4ml), blood circulation in the newborn is fairly intense and a large minute volume is provided by a high heart rate.