Your umbilical cord connects baby to the placenta for the exchange of oxygen and nutrients. It also carries waste products, like carbon dioxide, away from baby, so your body can process it and discard it. The umbilical cord extends 15-25 inches from the abdominal wall of fetus to placenta and can become knotted as the baby moves through loops of cord either throughout pregnancy or as they descend during birth. True knots in the umbilical cord happens in 0.3% to 2.1% of pregnancies. Blood, oxygen, and nutrients flow to the baby is protected by Wharton's jelly, a thick gel that cushions and supports the cord, keeping the blood vessels from being compressed.
This is a cord of a healthy baby born with Midwife Delmar in attendance. His cord had TWO true knots, seen here.