Although the term sounds scary, umbilical cord knots are not very common and even when they do occur, they usually pose little risk to you or your baby.

Read on for everything expectant moms need to know about cord knots, including the signs to look out for.

What are umbilical cord knots?

A cord knot is exactly what the term sounds like — a knot in the baby's umbilical cord. Some knots form during pregnancy as baby flips and turns in her amniotic sac; other knots form during delivery.

A substance called Wharton's jelly provides cushioning around the important blood vessels of the cord and protects them even if the cord gets knotted. This means that the odds are in your favor (and your baby's) that a "true" tight knot won't occur.

As long as the knot remains loose, it won't cause harm to your baby. But if the knot becomes tight, it could interfere with the circulation of blood from the placenta to the baby and cause oxygen deprivation. Such a complication is most likely to occur during your baby's descent through the birth canal, but these cases are rare.[1]

How common are umbilical cord knots?

While it's a good idea to watch for signs of a possible umbilical cord knot so you can alert your practitioner, they are not very common, occuring in about one in every hundred pregnancies.[2]

More common than knots are nuchal loops, the technical term for when the cord wraps around a baby's neck. Nuchal loops — also known as nuchal cords — occur in about 20 percent of all pregnancies but rarely pose risks to the baby.[3]

Who is most at risk for umbilical cord knots?

Babies with long umbilical cords and those who are small for their gestational age are at greater risk for developing true knots.

Carrying monoamniotic twins (identical twins that share the same amniotic sac), or having hydramnios may make a woman more prone to having a pregnancy with a cord knot.

What are the symptoms of cord knots?

The most common sign of a cord knot is decreased fetal activity after week 37. If the knot occurs during labor, a fetal monitor will detect an abnormal heart rate.

There is nothing you can do to prevent a knotted umbilical cord. You can, however, keep a general eye on how your baby is doing, especially later in your pregnancy, by doing regular kick counts and calling your practitioner if you notice any change in fetal activity.

If a loose knot tightens during delivery, your practitioner will be able to detect the drop in your baby's heart rate, and will make the appropriate decisions to ensure your baby's safe entry into the world. Immediate delivery, usually via C-section, is often the best approach.