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How does the umbilical cord connect an embryo to the placenta?

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A series of medical illustrations showing the stages of childbirth: the baby's position at the onset of labor, flexion, internal rotation of the head, extension, external rotation of the head, and the uterus immediately after birth with the placenta and umbilical cord. — birth Sequential changes in the position of the child during labour.

The umbilical cord is a narrow, tissue-based structure that connects a developing embryo or fetus to the placenta. It serves as the vital conduit for the fetal circulatory system to exchange nutrients, oxygen, and waste products with the mother.1

The cord contains three primary blood vessels:
* One umbilical vein: This vessel carries oxygenated blood and nutrients from the placenta to the fetus.12
* Two umbilical arteries: These carry deoxygenated blood and fetal waste products from the fetus back to the placenta for processing by the maternal body.12

Within the placenta, these vessels connect to a network of villi. Fetal blood flows through capillaries in these villi, which are bathed in maternal blood. This allows for the efficient diffusion of substances between the two bloodstreams without the blood actually mixing. After birth, the cord is clamped and cut, eventually leaving the navel.21