Pregnancy Complication: Differences in the Umbilical Cord and Placenta

What happens when your umbilical cord and placenta are different than expected? Get the facts on two-vessel cords and placenta previa.

pregnant belly in shadows

Sometimes, your umbilical cord and placenta may be different than they're "supposed" to be. But is that cause for concern? Here's what you need to know.

Two-Vessel Cords

First let's talk about that umbilical cord. Most cords have one vein and two arteries. The vein carries oxygenated blood from the placenta to the baby and the arteries carry deoxygenated blood from the baby to the placenta. In approximately 1% of pregnancies there are only two vessels —usually one vein and one artery. In about 75% of those cases, the baby is entirely normal and healthy and the missing artery isn't missed at all. It's that other 25% that causes so much worry.

Sometimes a two-vessel cord is a sign that the baby has other abnormalities—sometimes life threatening and sometimes not. If you have an umbilical cord with just two vessels, an ultrasound can be helpful to reassure you that your baby doesn't have any other glaring problems.

If your baby is in the 25% where the two-vessel cord is an indicator of other problems, you need more information. Your doctor will most likely refer you to a perinatolgist, an obstetrician who specializes in high-risk pregnancies. You'll have more ultrasounds and if you decide you want it, genetic testing. Depending on what information you receive, you will either be reassured that all's well or you'll find out more specifically what type of challenges your baby will have. Then there will be more decisions to make.

Some parents, when faced with a potentially "different" baby decide to do nothing. They figure they'll take it as it comes, meet this baby when he's born and deal with whatever happens. Others get all the info they can up front, do research, find resources and prepare themselves in advance. Still others, and this is a minority, decide they don't have the resources to raise a child with serious anomalies and terminate the pregnancy. No matter which avenue they take, this is a tough, tough time for parents who must give up the dream of having a "perfect" baby.

Let's get back to the other 75%—the one where the baby is just fine. There might be extra ultrasounds and checkups in your pregnancy to watch for intrauterine growth retardation. That's medical-speak for a baby who doesn't grow as big as we'd like in the uterus. That pesky 2-vessel cord is obviously attached to the placenta and if baby's not getting adequate oxygen and nutrition through it, your baby might not grow well.

What do we do then? We keep a close eye on baby and deliver him/her as soon as we can ascertain he/she's old enough to grow better outside the uterus than inside. This baby might end up in a special-care nursery or might just get out into her mother's arms, breastfeed like a fiend and grow beautifully. That's a wait and see situation.

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Placenta Previa

Now, about that placenta. That placenta is baby's best friend, source of blood supply, oxygen, food, everything. We need it to be safe, healthy and to hang on for the whole pregnancy.

If it's covering the cervix, that's called a placenta previa. Babies can't be delivered through a placenta-covered cervix because it will destroy the placenta leaving mother and baby at risk for hemorrhage. It has to stay in good working order all the way through delivery. Once baby's born, fine—retire, already. Just not one moment sooner.

Most of the time however, as the lower uterine segment grows, it outpaces the placenta, essentially moving the cervix away from it. Once the placenta is clear of the cervix, there's no longer any danger. If it doesn't move out of the way—that's a darn good reason to have a cesarean section. There's no other way to safely deliver the baby. You're also looking at bed rest through the third trimester to decrease chances of bleeding. If you have a placenta previa, you may just have to wait and see what happens with the placenta over the next couple months.

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