What Does the Umbilical Cord Do?

Your baby's umbilical cord—or their lifeline, as it's sometimes called—connects you to your baby via the placenta. While the primary role of the umbilical cord is carrying nutrients and oxygen to your baby's body, it also gets rid of any waste material.

The umbilical cord begins developing around four weeks of pregnancy and can grow to about 22 inches long. Here's what you need to know about your baby's umbilical cord, including why it's important, signs of a healthy umbilical cord, and when it may fall off.

What Is the Umbilical Cord?

Your baby's umbilical cord is a tube-like structure that contains three blood vessels, explains Amber Samuel, M.D., a board-certified maternal-fetal medicine specialist and the medical director at Pediatrix Medical Group. These blood vessels consist of two uterine arteries that carry waste from your baby back to the placenta, along with one vein that carries food and oxygen from the placenta to your baby.

The umbilical cord is necessary for your baby to live, grow, and develop while in the uterus, says Asnat Walfisch, M.D., an OB-GYN and the director of obstetrics and gynecology at Beilinson Hospital. "Once the baby is born and can breathe air and consume milk, the cord is no longer necessary."

Why Is the Umbilical Cord Important?

The umbilical cord is often called your baby's lifeline for good reason. It brings the building blocks of cells, glucose, and oxygen, and removes waste products like carbon dioxide from your baby, explains Dr. Samuel. Without it, no pregnancy could continue, as there would be no connection between the pregnant person's circulation and the baby, she adds.

Without the umbilical cord, your baby can't get oxygen or nutrition, says Wendy Goodall McDonald, M.D., a board-certified obstetrician and gynecologist and published author. "The umbilical cord is as important as our ability to breathe."

Signs of a Healthy Umbilical Cord

Even though you cannot detect your baby's umbilical cord health just from looking at your pregnant belly, its development is easily tracked with an ultrasound, says Dr. Samuel. "We examine the cord, its position in relation to the placenta, the fetal abdomen, and the cervix, and evaluate for normal structure, number of vessels, and any signs of knots or cysts."

Typically, a person receiving regular prenatal care with ultrasounds can expect signs of fetal development to be checked as early as 12 weeks, notes Dr. Samuel. Then, at the anatomy ultrasound—which usually occurs around 20 weeks of pregnancy—the cord can be checked as well.

"Most of the time, the umbilical cord is very strong due to its protective gelatinous covering," explains Michael Platt-Faulkner, D.O., an OB-GYN at St. Elizabeth's Healthcare. "There are certain conditions where the umbilical cord connects abnormally to the placenta or where the protective jelly covering the umbilical cord can be missing. In these cases, the cord can be more fragile. Thankfully, abnormalities of the umbilical cord are typically able to be visualized on ultrasound and additional testing and monitoring can be performed if needed."

A healthy umbilical cord should have three total blood vessels and insert into the middle portion of the placenta, adds Dr. Platt-Faulkner. "Sometimes, one of the vessels in the cord is missing. While this typically does not cause problems during pregnancy or delivery, additional testing and monitoring may be ordered if abnormalities of the cord are noted during an ultrasound."

When Does the Umbilical Cord Fall Off?

The umbilical cord is usually cut within the first few minutes of life, but a small portion will still be attached. This smaller piece of cord usually falls off between 10 and 14 days after your baby is born. However, it can take as long as 21 days. And, even if it falls off before seven days, that is normal and nothing to worry about.

While you are waiting for the cord to fall off, your only role is to keep the stump clean and dry. For this reason, pediatricians typically recommend giving your baby a sponge bath. You should, however, check your baby's skin around the base of the cord once a day to look for redness or any unusual drainage. Pediatricians also recommend that you roll your baby's diaper down and away from the cord clamp, and dress your baby gently to avoid too much friction in the abdomen area.

Also, keep in mind that as your baby's cord dries up, it may change color. Umbilical cords can go from a shiny yellowish tint to brown or even gray. This is normal and part of the drying process. But if you are concerned, don't hesitate to contact a pediatrician or health care provider. They can let you know if your baby's umbilical cord is progressing normally.

When to Call a Health Care Provider

Most of the time, the umbilical cord functions as it should, and there is nothing to worry about. Even true knots in the umbilical cord, which occur in less than 1% of births, are usually not a huge cause for concern.

That said, if you are pregnant and notice your baby is moving around less than normal, it could be a sign of an issue with the umbilical cord. "During pregnancy, notify a health care provider for decreased or absent fetal movement," advises Dr. Samuel.

After your baby is born, you can expect the cord to dry up and fall off as it should. If your baby's cord has not fallen off after three weeks, you may want to reach out to your a provider. You also should reach out if your baby has a small red mass of scar tissue (or a granuloma) that stays on their belly button after the cord has fallen off. While this condition often goes away on its own, if it persists, a health care provider may need to cauterize the tissue.

Other signs of potential issues with the cord include redness, swelling, pus or other discharge, and a foul smell. Some babies might cry when the area near the cord is touched. If you notice any of these signs, contact a pediatrician or health care professional as they might indicate an infection, says Dr. McDonald.

"Sometimes there may be a normal discharge from the base of the stump and it may have a slight odor," she adds. "But If you notice anything more pungent, there's nothing wrong with checking on it."