Q&A: Our baby's umbilical cord has two vessels instead of three. How serious is this?

Normally the umbilical cord has two arteries to carry oxygenated blood toward the baby, and one large vein to carry de-oxygenated blood out toward the placenta. So, three total. As a side note, this is the opposite functioning of arteries and veins from what happens in circulation after birth.

In a two-vessel cord, the cord has one less artery, being composed of one vein and one artery. Problems associated with a two-vessel cord, when noted by ultrasound, include abnormalities of cardiovascular, gastrointestinal, and central nervous system. But the most recent studies indicate that the chance of abnormalities in a baby with a two-vessel cord is only seven percent. This means that there's a 93 percent chance of no abnormalities at all.

In these situations, in spite of the odds being in your favor, your health care provider may suggest a "Level III" ultrasound by a specialist in maternal-fetal medicine just to make sure your baby is developing normally.