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When the baby is born, the lungs are needed for oxygen transfer and need high blood flow which is encouraged by low PVR. The failure of the circulatory system of the newborn to adapt to these changes by lowering PVR leads to persistent fetal circulation. [2] The newborn is therefore born with elevated PVR, which leads to pulmonary hypertension.
Manifestations: When the newborn cries, there is a reversal of blood flow through the foramen ovale which causes the newborn to appear mildly cyanotic in the first few days of life. The heart rate of the newborn should be between 110 and 160 beats per minute and it is common for the heart rate to be irregular in the first few hours following birth.
It is estimated that less than 1ml of fetal blood is lost to the maternal circulation during normal labour in around 96% of normal deliveries. [1] [2] The loss of this small amount of blood may however be a sensitising event and stimulate antibody production to the foetal red blood cells, an example of which is Rhesus disease of the newborn.
The effect of pregnancy on platelet count is unclear, with some studies demonstrating a mild decline in platelet count and other studies that show no effect. [24] The white blood cell count increases with occasional appearance of myelocytes or metamyelocytes in the blood. [24] During labor, there is a rise in leukocyte count.
Since blood flows from high to low pressure systems, the direction of blood flow across the ductus arteriosus reverses. As the oxygen-rich blood from the aorta flows across the ductus arteriosus to the pulmonary artery, the ductus arteriosus will constrict in response to the high oxygen content of the blood.
Histopathology of placenta with increased syncytial knotting of chorionic villi, with two knots pointed out. The following characteristics of placentas have been said to be associated with placental insufficiency, however all of them occur in normal healthy placentas and full term healthy births, so none of them can be used to accurately diagnose placental insufficiency: [citation needed]
During pregnancy, the mother's circulatory system delivers oxygen and nutrients to the fetus and carries away nutrient-depleted blood enriched with carbon dioxide. The maternal and fetal blood circulations are separate and the exchange of molecules occurs through the placenta, in a region called intervillous space which is located in between ...
[13] [14] Blood typing would also detect maternal blood, as the I antigen only occurs in adults. [12] The Kleihauer–Betke test can detect very small amounts of maternal blood before the third trimester of pregnancy by monitoring hemoglobin elution in acid because adult and fetal hemoglobin elute differently in acid. [12]