What will take place in the umbilical cord when the baby first fully uses the lungs?

Answer 1

Fetal Circulatory System

The baby's circulatory system works differently when he's in the womb than it does after birth.

During pregnancy, the mother's placenta transfers nutrients and highly oxygenated blood to the fetus through a single, large vein in the umbilical cord, and removes deoxygenated blood and waste products through two smaller umbilical arteries. The returned blood is filtered through the placenta back into the mother's circulatory system, and eliminated. This process is necessary because the fetus can't breath until he (or she) is born.

The large umbilical vein passes through the baby's abdomen to his liver, where it divides into three smaller branches. Two supply blood to the liver, and the third connects to the inferior vena cava (IVC), a major vein that carries blood to the heart.

The heart is divided into four chambers: the bottom two chambers are called ventricles, and the top two are called atriums. The IVC enters the heart at the right atrium.

In an adult, the left and right sides of the heart are closed off from each other. The right side of the heart recirculates deoxygenated blood back to the lungs via the pulmonary artery, while the left side receives oxygenated blood from the lungs and pumps it out to the rest of the body.

Since the fetus doesn't use his lungs for breathing, he only needs a little blood to keep the lung tissue healthy, while preventing the wet and delicate lungs from being overwhelmed by too much blood at too high pressure. The developing body and brain, on the other hand, can make good use of the oxygenated blood. For this reason, the fetal heart develops with a hole (called the foramen ovale) between the right and left atriums that allows more blood to be diverted away from the lungs to the rest of the body. There is also a short tube (called the ductus arteriosis) connecting the pulmonary artery to the aorta that helps perform the task of shunting blood away from the lungs.

What happens after birth:

When the baby's born, the umbilical cord is cut and clamped, so it's no longer part of his circulatory system.

The baby's first breaths create pressure changes in his circulatory system that reduce blood flow through the two ducts (the foramen ovale and the ductus arteriosis). These will usually close permanently over the next few days to weeks.

The empty umbilical vessels collapse because there is no blood pressure to keep them dilated.

Outside the body, the umbilical cord, with its collapsed veins and arteries, no longer has a blood supply, so it dries out (like an unwatered plant) while the place where the veins and arteries passed through into the baby's body heals and begins to form a scar called the naval (or belly button).

In most cases, the cord will dry out and fall off within 10 days to three weeks. Some practitioners recommend cleaning the stump with rubbing alcohol and swabs, while others recommend letting the cord dry naturally. Always follow your pediatrician's advice.

On occasion, the stump doesn't dry out as quickly as it should, and the pediatrician may decide to cauterize (burn) the stump with silver nitrate sticks. Because there are no nerve endings in the severed cord, this treatment is painless.