The blood that flows through the fetus is actually more complicated than after the baby is born normal heart. The placenta accepts the bluest blood 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 and becomes red. The red blood then returns to the fetus via the third vessel in the umbilical cord umbilical vein. The red blood that enters the fetus passes through the fetal liver and enters the right side of the heart.
Let's start off by comparing and contrasting the fetal circulation with the adult circulation. This is going to be an important process because during birth there are a lot of things that are changing especially for the fetal circulation. So let's start with the items that are very different between the two, fetus and adult. The big ones are the lungs. The final really big change that happens between the fetus and the adult is the placenta. So let's talk about why these differences exist.
Fetal circulation differs from the adult circulation due to the presence of certain vessels and shunts. These shunts will close after birth, and most of these fetal vessels will be seen as remnants in the adult circulation. The function of these shunts is to direct oxygen-rich venous blood to the systemic circulation and to ensure oxygen-deplete venous blood bypasses the underdeveloped pulmonary circulation.
Fetal circulation is the circulation of blood through the cardiovascular system in the human fetus. It's well known that the blood circulation in the humans varies. When the embryo develops into the fetus, it creates a functional cardiovascular system that cooperates with the mother's system. During birth, there are functional physiological changes that transform the shared system into an individual one for the fetus.