What is the main purpose of the umbilical cord?

The umbilical cord primarily serves as a lifeline for the developing fetus, facilitating the transfer of essential nutrients and oxygen from the placenta directly to the fetus. This connection is critical for the fetus's growth and development, as it relies entirely on the maternal blood supply for these vital substances. The umbilical cord also contains blood vessels—typically two arteries and one vein—that effectively transport deoxygenated blood and waste products away from the fetus while bringing back oxygen-rich blood and nutrients.

While the umbilical cord does connect the fetus to the maternal blood supply, this function is best encapsulated by the transport of nutrients and oxygen; hence, the emphasis on the direct role of the cord in providing these essentials. Additionally, while the umbilical cord plays a role during the birth process, such as delivering the placenta, its primary function is not to assist in this process. Finally, although the fetus is somewhat protected from infections by the amniotic fluid and placenta, the cord is not primarily designed for this purpose. Thus, the main purpose of the umbilical cord is accurately reflected in its role of providing nutrients and oxygen from the placenta to the fetus.