What is the umbilical cord?
The umbilical cord is a tube that connects you to your baby during pregnancy. It has three blood vessels: one vein that carries food and oxygen from the placenta to your baby and two arteries that carry waste from your baby back to the placenta. A substance called Wharton’s jelly cushions and protects these blood vessels. The umbilical cord starts to form at about 4 weeks of pregnancy and usually grows to be about 22 inches long.
Umbilical cord conditions include the cord being too long or too short, not connecting well to the placenta or getting knotted or squeezed. These conditions can cause problems during pregnancy, labor and birth.
If you have one of these conditions, your health care provider may find it during pregnancy on an ultrasound. An ultrasound is a prenatal test that uses sound waves and a computer screen to show a picture of your baby inside the womb.
What is umbilical cord prolapse?
Umbilical cord prolapse is when the umbilical cord slips into the vagin* (birth canal) ahead of your baby during labor and birth. The cord can get pinched, so your baby may not get enough oxygen. This happens in about 1 in 300 births (less than 1 percent of births).
You may be at risk for umbilical cord prolapse if:
- Your baby is preterm. This means he’s born before 37 weeks of pregnancy. Babies born this early may have more health problems at birth and later in life than babies born on time.
- Your baby is low birthweight. This means he weighs less than 5 pounds, 8 ounces at birth.
- Your baby is in a breech position. This means he’s not head-down for labor and birth.
- The umbilical cord is too long.
- Your provider ruptures your membranes to start or speed up labor. Membranes are the tissue that connect the amniotic sac to the uterus (womb).
- You have too much amniotic fluid. This condition is called polyhdramnios.
- You’re having twins or more.
For most babies, umbilical cord prolapse doesn’t cause problems. But if your baby’s not getting oxygen because the cord is pinched, it can cause stillbirth unless your baby’s born right away. Stillbirth is when a baby dies in the womb after 20 weeks of pregnancy.
If your water breaks and you feel something in your vagin*, go to the hospital right away. Your provider can look for cord prolapse by checking your baby’s heart rate and doing a pelvic exam on you. He may be able to take pressure off the umbilical cord by moving the baby. If the cord is pinched, you may need to have a Cesarean section (also called c-section) instead of a vagin*l birth. A c-section is surgery in which your baby is born through a cut that your doctor makes in your belly and uterus. A vagin*l birth is the way most babies are born - it’s when your uterus contracts to push your baby out through the vagin*.
What is a single umbilical artery?
Single umbilical artery is when one artery in the umbilical cord is missing. It happens in about 1 in 100 singleton pregnancies (1 percent) and about 5 in 100 multiple pregnancies (5 percent). A singleton pregnancy is when you’re pregnant with just one baby. A multiple pregnancy means you’re pregnant with more than one baby (twins, triplets or more). We don’t know what causes single umbilical artery.
About 2 in 10 babies (20 percent) with a single umbilical artery have health problems, including heart, kidney or digestion problems and genetic conditions. Digestion is the process of how your body breaks down food after you eat. A genetic condition is caused by a gene that’s changed from its regular form. A gene can change on its own, or the changed gene can be passed from parents to children.
If an ultrasound shows that you have a single umbilical artery, your provider may recommend checking your baby’s health during pregnancy with these tests:
- A detailed ultrasound of your baby
- Amniocentesis. In this test, your provider takes some amniotic fluid from around your baby in the uterus (womb). The test checks for birth defects and genetic conditions in your baby. You can get this test at 15 to 20 weeks of pregnancy. Birth defects are health conditions that are present at birth. They change the shape or function of one or more parts of the body. They can cause problems in overall health, in how the body develops or in how the body works.
- Echocardiogram. This is a special ultrasound that check’s your baby’s heart.
What is vasa previa?
Vasa previa is when one or more blood vessels from the umbilical cord or placenta cross the cervix. The cervix is the opening to the uterus (womb) that sits at the top of the vagin*. These blood vessels aren’t protected by the umbilical cord or the placenta, so they can tear during labor. This can cause life-threatening bleeding in your baby. Torn blood vessels cause death in at least half of babies with vasa previa. Even if the blood vessels don’t tear, pressure on them during labor can cause problems for your baby.
Your provider may find vasa previa on an ultrasound or during a pelvic exam during your pregnancy. When this happens, you may need to have a c-section to help make sure your baby’s born safely.
Vasa previa is rare; it happens in just 1 in 2,000 to 3,000 births (much less than 1 percent of births). We don’t know what causes it, but you may be at risk for it if you:
- Have a velamentous insertion of the umbilical cord. This is when the umbilical cord doesn’t connect correctly to the placenta.
- Have placenta problems like placenta previa. This is when the placenta is very low in the uterus and covers all or part the cervix.
- Are pregnant with more than one baby
What is a nuchal cord?
A nuchal cord is an umbilical cord that gets wrapped around a baby’s neck. Babies with a nuchal cord usually are born healthy, but it sometimes can affect their heart rate. Your provider can see a nuchal cord on an ultrasound and usually can slip the cord off the baby’s neck during labor and birth.
What are umbilical cord knots?
Knots in umbilical cords can form early in pregnancy when your baby moves around in the womb. Knots happen most often when the umbilical cord is too long and in pregnancies with identical twins. Identical twins share one amniotic sac, which makes it easy for the babies' umbilical cords to get tangled. The amniotic sac (also called bag of waters) is inside the uterus (womb) and is filled with amniotic fluid. About 1 in 100 pregnancies (about 1 percent) have a knot in the umbilical cord.
If a knot gets pulled tight, it can cut off your baby’s oxygen. This can cause miscarriage or stillbirth. Miscarriage is when a baby dies in the womb before 20 weeks of pregnancy. Your provider looks for umbilical cord knots on your ultrasound. If you have a knot, you may need to have a c-section to help keep your baby safe.
What is an umbilical cord cyst?
Umbilical cord cysts are sacs of fluid in the umbilical cord. They’re not common—less than 1 in 100 pregnancies (less than 1 percent) has an umbilical cord cyst. Your provider may find an umbilical cord cyst during an ultrasound. She’s more likely to find them in the first trimester than in the second or third trimesters. Most cysts found in the first trimester don’t hurt the baby.
There are two kinds of cysts:
- True cysts contain fluid from the original embryo that developed into your baby. These cysts usually go away on their own and are located close to where the umbilical cord connects to the baby.
- Pseudocysts (also called false cysts) are more common than true cysts. They’re found anywhere along the umbilical cord. The fluid in the cysts comes from Wharton’s jelly. These cysts may be linked to genetic conditions in your baby.
If your provider finds a cord cyst during an ultrasound, she may recommend additional tests, like amniocentesis, a detailed ultrasound and genetic tests to check for birth defects. If your cysts are large, you may need to have a c-section to keep the cysts from breaking, which can cause problems for your baby during labor and birth.
Last reviewed: June, 2016
