WordNet
n. the system of blood vessels and structures through which blood moves in a fetus [syn: foetal circulation]
Wikipedia
In animals that give live birth, the fetal circulation is the circulatory system of a fetus. The term usually encompasses the entire fetoplacental circulation, which includes the umbilical cord and the blood vessels within the placenta that carry fetal blood.
The fetal (prenatal) circulation works differently from normal postnatal circulation, mainly because the lungs are not in use. Instead, the fetus obtains oxygen and nutrients from the mother through the placenta and the umbilical cord. The advent of breathing and the severance of the umbilical cord prompt various neuroendocrine changes that shortly transform fetal circulation into postnatal circulation.
The fetal circulation of humans has been extensively studied by the health sciences. Much is known also of fetal circulation in other animals, especially livestock and model organisms such as mice, through the health sciences, veterinary science, and life sciences generally.