Two-Vessel Cord

What is a two-vessel umbilical cord?

Most babies’ umbilical cords have three blood vessels: one vein, which brings nutrients from the placenta to baby, and two arteries that bring waste back to the placenta. But a two-vessel cord has just one vein and one artery -- that's why the condition is also referred to as having a single umbilical artery.

What are the signs of a two-vessel umbilical cord?

There usually aren’t any before it’s diagnosed.

Are there any tests for a two-vessel umbilical cord?

Yes. During your midpregnancy ultrasound, the doctor will check to see whether there are three vessels in the umbilical cord.

How common is a two-vessel umbilical cord?

It’s much more common than you probably think it is -- it happens in about 1 to 1.5 percent of all pregnancies.

How did I get a two-vessel umbilical cord?

We wish we had answers, but there’s no known cause of a two-vessel cord.

How will my two-vessel umbilical cord affect my baby?

In most cases, it won’t: The one artery just makes up for what the missing one would do. However, there’s a slight increase in risk of growth problems and a minimal increase in risk of stillbirth.

You should also be aware that baby’s kidneys and heart develop at the same time as the umbilical cord does, so there’s also a slight increase in risk of abnormalities to those organs. Your doctor will look closely at the kidneys and heart and may have a specialist give baby an echocardiogram in the late second trimester to be sure everything’s okay.

There used to be a belief that a two-vessel cord signaled an increased risk of chromosomal abnormalities like Down syndrome, but that’s actually not true -- those would be more likely to be signaled by other symptoms, and your doc would look at other factors to diagnose something like that. Most of the time, baby’s perfectly healthy.

See Next Page for treatments, prevention and more advice.

-- Brian Iriye, MD, ob-gyn and member of the Society for Maternal-Fetal Medicine