Definition,
The blood circulation in the fetus (an unborn baby). Before birth, blood from the fetal heart that is destined for the lungs is shunted away from the lungs through a short vessel called the ductus arteriosus and returned to the aorta.
Type of fetal circulation,
The fetal circulatory system uses two right to left shunts, which are small passages that direct blood that needs to be oxygenated. The purpose of these shunts is to bypass certain body parts? in particular, the lungs and liver ? that are not fully developed while the fetus is still in the womb.
Fetal circulation
The blood that flows through the fetus is actually more complicated than after the baby is born (normal heart). This is because the mother (the placenta) is doing the work that the baby’s lungs will do after birth.
The placenta accepts the blood without oxygen from the fetus through blood vessels that leave the fetus through the umbilical cord (umbilical arteries, there are two of them). When blood goes through the placenta, it picks up oxygen. The oxygen rich blood then returns to the fetus via the third vessel in the umbilical cord (umbilical vein). The oxygen rich blood that enters the fetus passes through the fetal liver and enters the right side of the heart.
The oxygen rich blood goes through one of the two extra connections in the fetal heart that will close after the baby is born.
The hole between the top two heart chambers (right and left atrium) is called a patent foramen ovule (PFO). This hole allows the oxygen rich blood to go from the right atrium to left atrium and then to the left ventricle and out the aorta. As a result, the blood with the most oxygen gets to the brain.
Blood coming back from the fetus’s body also enters the right atrium, but the fetus is able to send this oxygen poor blood from the right atrium to the right ventricle (the chamber that normally pumps blood to the lungs). Most of the blood that leaves the right ventricle in the fetus bypasses the lungs through the second of the two extra fetal connections, known as the ductus, arteriosus.
The ductus arteriosus sends the oxygen poor blood to the organs in the lower half of the fetal body. This also allows for the oxygen poor blood to leave the fetus through the umbilical arteries and get back to the placenta to pick up oxygen.
Since, the patent foramen ovule and ductus, arteriosus are normal findings in the fetus, it is impossible to predict "whether" or not these connections will close normally after birth in a normal fetal heart. These two bypass pathways in the fetal circulation make it possible for most fetuses to survive pregnancy even when there are complex heart problems and not be affected until after birth when these pathways begin to close.
Results,
Through, the blood vessels in the umbilical cord, the fetus gets all needed nutrition and oxygen. The fetus gets life support from the mother through the placenta. Waste products and carbon dioxide from the fetus are sent back through the umbilical cord and placenta to the mother's circulation to be removed.
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