An umbilical cord is a lifeline for a baby in the womb. Running from the baby’s abdomen to the placenta, the umbilical cord usually contains three blood vessels and is about 21” long. It provides oxygen, blood, and nutrients to the developing fetus. However, later in pregnancy many women fear the thought of the umbilical cord wrapping around the baby’s neck and the possibility of problems during delivery or even a stillbirth.
Pregnant women: Breathe a sigh of relief. Nuchal cords are surprisingly common and unlikely to cause problems during pregnancy or at birth. Estimates suggest that 20 to 30 percent of all deliveries involve a nuchal cord. And a 2018 study in the American Journal of Obstetrics and Gynecology reports that, the majority of time, babies do just fine when one is present.
What causes nuchal cords?
Random fetal movement is the primary cause of a nuchal cord. Other factors that might increase the risk of the umbilical cord wrapping around a baby’s neck include an extra-long umbilical cord or excess amniotic fluid that allows more fetal movement.
Nuchal cords typically are discovered at birth. Occasionally, patients ask if we can see them on ultrasound, which sometimes we can. There’s no way yet to prevent nuchal cords or unwind them from a baby’s neck in the womb. But when a baby is born with a nuchal cord, your doctor will know what to do because it happens so frequently.
When is a nuchal cord dangerous?
If the cord is looped around the neck or another body part, blood flow through the entangled cord may be decreased during contractions. This can cause the baby’s heart rate to fall during contractions. Prior to delivery, if blood flow is completely cut off, a stillbirth can occur.
In the 2018 study, 12 percent of deliveries had a nuchal cord. Most babies with a nuchal cord had just a single loop around the neck. Fortunately, there was no increased risk for growth problems, stillbirth, or lower Apgar scores in this group.
What happens during delivery?
Since the vast majority of time we don’t know if a baby will have a nuchal cord, it is routine that the doctor will check the baby’s neck for a nuchal cord after the baby’s head is delivered. Usually the cord is loose and can be slipped over the baby’s head. At times it might be too tight to easily slip over the head, and the doctor or midwife will clamp and cut the cord before the baby’s shoulders are delivered. This keeps the cord from tearing away from the placenta when the rest of the baby’s body is delivered.
Remember, a nuchal cord is common, and complications caused by the condition are rare. If you’ve been told your baby has a nuchal cord and you have questions, call us at 214-645-8300 or request an appointment online.