What Is The Umbilical Cord For In Pregnancy?

The umbilical cord is your baby’s lifeline during pregnancy. It is a flexible tube that connects your developing baby to the placenta, carrying oxygen and nutrients from your bloodstream to your baby, and carrying waste products back out. Without it, a fetus could not grow or survive inside the womb.

Most people do not think about the umbilical cord until delivery. But it is working from the earliest weeks of pregnancy, and its structure and function are more interesting than most people realize.

What Is The Umbilical Cord For In Pregnancy?

The cord is the only physical connection between the fetus and the placenta. Everything the baby needs to grow passes through it.

The placenta attaches to the wall of your uterus and acts as a temporary organ. It pulls oxygen and nutrients from your blood. Those substances then travel through the umbilical cord to your baby. At the same time, waste products like carbon dioxide travel back through the cord to the placenta, where they are passed into your bloodstream for your body to clear.

The cord also carries blood with different oxygen levels in two directions at once. That is unusual. In adults, arteries carry oxygen-rich blood away from the heart and veins carry oxygen-poor blood back. In the umbilical cord, it is the opposite. The umbilical vein carries oxygen-rich blood from the placenta to the baby. The two umbilical arteries carry oxygen-poor blood and waste from the baby back to the placenta.

This system works because a fetus does not use its lungs to breathe. The lungs are filled with fluid and are not yet functional for gas exchange. All breathing happens through the placenta and cord until birth.

How Does the Umbilical Cord Develop?

The cord forms very early in pregnancy. By about the fifth week of gestation, the basic structures that will become the cord are already in place. It develops from the same cluster of cells that gives rise to the placenta.

A normal umbilical cord contains three blood vessels: one vein and two arteries. These vessels are surrounded by a jelly-like substance called Wharton’s jelly. This jelly protects the vessels from being compressed or kinked. It also keeps the cord slippery so it can move freely without tangling around itself too tightly.

By the time a baby is born, the average cord is about 20 to 24 inches long and roughly the thickness of a finger. Length varies widely. Some cords are much shorter, and some are longer. Cord length is not something a pregnant person can control or influence.

What Can Go Wrong With the Umbilical Cord?

Most cords function normally throughout pregnancy. But several cord-related issues can occur, and some carry real risks.

Single umbilical artery. Instead of two arteries, the cord has only one. This occurs in roughly 1 in 100 pregnancies, though estimates vary. It is sometimes linked to other birth defects, but many babies with a single umbilical artery are born healthy. When it is found, doctors usually recommend closer monitoring.

Nuchal cord. The cord wraps around the baby’s neck one or more times. This sounds alarming, but it is common and often harmless. The cord is slippery and cushioned, so a loose wrap usually does not compress the vessels. In many cases, it is only discovered at delivery and causes no problems. A tight nuchal cord is a different situation and may require attention during labor.

Cord prolapse. The cord slips through the cervix ahead of the baby during labor. This is rare but serious. It can cut off blood flow to the baby. Cord prolapse is considered an emergency and usually requires immediate delivery, often by cesarean section.

Vasa previa. Blood vessels from the cord run across the opening of the cervix instead of being protected by the cord or placenta. This is rare but dangerous if the vessels tear during labor. It is often detected on prenatal ultrasound, which allows doctors to plan a cesarean delivery before labor begins.

Cord knots. True knots in the umbilical cord are uncommon. Some form early in pregnancy when the baby moves through a loop of cord. Many true knots are loose and cause no issues. Tight knots can restrict blood flow, but this is rare.

Can You Prevent Umbilical Cord Problems?

There is no proven way to prevent most cord problems. Cord length, cord position, and knots are not things a pregnant person can control through diet, exercise, or lifestyle.

What you can do is attend your prenatal appointments. Ultrasound can sometimes detect issues like vasa previa or a single umbilical artery. Regular monitoring helps your care team catch problems early.

If you notice decreased fetal movement, contact your healthcare provider right away. Movement changes can sometimes signal a problem with the cord or placenta. This is not something to wait on.

Some people ask about yoga poses, sleep positions, or specific exercises to prevent the cord from wrapping around the baby’s neck. No clinical evidence supports these claims. A nuchal cord is not caused by anything the mother did or did not do.

What Happens to the Umbilical Cord at Birth?

After your baby is born, the cord is clamped and cut. This is a routine part of delivery. The clamp stops blood flow between the baby and the placenta.

The timing of clamping has been studied. Delayed cord clamping, which means waiting at least one minute after birth before clamping, allows more blood to flow from the placenta to the baby. Research consistently shows that delayed clamping increases the baby’s iron stores in the first months of life. Major medical organizations now recommend delayed clamping for most healthy births, though the exact timing may vary based on the situation.

For premature babies, delayed clamping may reduce the risk of certain complications, though the evidence continues to evolve. Your delivery team will decide based on your specific circumstances.

After the cord is cut, a small stump remains on the baby’s belly. It dries out and falls off on its own, usually within one to three weeks. Keeping the stump clean and dry is the standard advice. There is no need to apply anything to it unless your pediatrician recommends otherwise.

What Is Wharton’s Jelly and Why Does It Matter?

Wharton’s jelly is the protective substance inside the umbilical cord. It surrounds the blood vessels and keeps them from collapsing or kinking.

This jelly is made of a specialized connective tissue rich in a compound called hyaluronic acid. It gives the cord a firm but flexible consistency. Without it, the cord could easily be compressed by the baby’s movements or by pressure inside the uterus.

Wharton’s jelly also has some immune properties. It contains substances that help protect the cord from infection. This is one reason the cord rarely becomes infected during pregnancy.

Researchers have studied Wharton’s jelly as a potential source of stem cells. Some early research suggests these cells may have therapeutic potential, but this is still experimental. No established clinical treatments currently use Wharton’s jelly stem cells.

Does the Umbilical Cord Have Any Other Functions?

The cord’s main job is transport. But it also plays a role in fetal movement and development.

Because the cord is flexible and slippery, it allows the baby to move freely in the amniotic fluid. This movement is important for muscle and bone development. The cord grows with the baby and accommodates the changing positions of the fetus throughout pregnancy.

The cord also helps regulate blood flow between the fetus and placenta. The vessels in the cord can constrict or dilate in response to certain signals, though this regulation is not fully understood.

One interesting detail: the umbilical cord has no nerve endings. That means cutting it at birth does not cause pain to the baby or the mother. The cord is a lifeline, but it is not a sensory organ.