Birth stage three, which begins after the birth of the baby, further contractions expel the placenta, amniotic sac, and the remaining portion of the umbilical cord usually within a few minutes. Enormous changes take place in the newborn's circulation to enable breathing in air. In the uterus, the unborn baby is dependent on circulation of blood through the placenta for sustenance including gaseous exchange and the unborn baby's blood bypasses the lungs by flowing through the foramen ovale, which is a hole in the septum dividing the right atrium and left atrium. After birth the umbilical cord is clamped and cut,
Medial umbilical ligament Medial umbilical ligament The medial umbilical ligament (or cord of umbilical artery) is a paired structure found in human anatomy. It is on the deep surface of the anterior abdominal wall, and is covered by the medial umbilical folds ("plicae umbilicales mediales"). It should not be confused with the median umbilical ligament, a different structure that represents the remnant of the embryonic urachus. It represents the remnant of the fetal umbilical arteries, which serves no purpose in humans after birth, except for the initial part that becomes the adult superior vesical artery. It may be used as a landmark for