Although common, the umbilical cord wrapping around a baby’s neck in the womb can raise concerns for parents and medical professionals. Medically known as a nuchal cord, this circumstance generally does not cause complications at birth. However, there are instances when a nuchal cord can result in serious consequences.
The umbilical cord wrapping around the neck of the fetus, also known as a nuchal cord, occurs in about 1 in 4 births.
Nuchal cords are common and do not usually cause complications during the delivery. A normal vaginal delivery is still possible when the cord is wrapped around the neck.
There are two types of nuchal cords. Type A (an unlocked cord) and Type B (a locked cord). Type B is less common but poses more risks to the fetus.
Although rare, the most severe complication of a nuchal cord is the death of the fetus, also known as a stillbirth.
There is no way to prevent or treat a nuchal cord. If the nuchal cord compromises the well-being of the fetus, a cesarean section may be necessary if appropriate.
When should parents be concerned? Can a vaginal delivery occur, or is a cesarean section required? Here is a breakdown of what you should know about a nuchal cord.
What is the umbilical cord?
The umbilical cord is the lifeline between the mother and the fetus. It is a long, tube-like, squishy cord that contains the blood vessels necessary to deliver blood, oxygen, and nutrients to the fetus. The cord connects from the placenta (an organ that forms within the uterus during pregnancy) to the abdomen of the fetus. After delivery, the cord is cut, and the remaining piece of tissue on the baby eventually dries up, falls off, and becomes the belly button.
Types of the nuchal cord
The nuchal cord is a term used to describe when the umbilical cord randomly wraps around the neck of a fetus as it moves around inside the uterus and changes position throughout the pregnancy. If the cord is unusually longer than average, there is a presence of excess amniotic fluid surrounding the fetus, or there are multiple fetuses (twins, triplets, etc.), the chances of the cord wrapping around the neck can increase.
There are two types of a nuchal cord:
- Type A. In this case, the area of the cord closest to the placenta crosses over the cord closest to the umbilical area. This type is also called an unlocked nuchal cord, as it comes undone more easily. This type of nuchal cord occurs more commonly.
- Type B. In this case, the area of the cord closest to the umbilicus wraps around the cord closest to the placenta and is known as a locked nuchal cord because it is less likely to undo itself. Type B is less common but is the more serious of the two and can result in a true knot.
The cord can wrap around the neck just once or multiple times. If the cord wraps around three or more times, the incidence of fetal death increases. The presence of a nuchal cord does not always indicate the need for a cesarean section. Many times, a normal vaginal delivery can still occur with a nuchal cord present.
What causes a nuchal cord?
Research suggests that around 1 in 4 deliveries have a nuchal cord present. The likelihood of the cord wrapping around the neck increases with gestational age because as the fetus grows, the space within the uterus becomes more cramped, so the cord is not able to move around as freely. There are two types of nuchal cords, type A and type B, and they vary depending on how the cord is positioned around the neck.
Complications of a nuchal cord
Although the majority of nuchal cords do not cause any complications to the fetus, there are some instances when the risk for severe complications can occur. Some of the potential risks of a nuchal cord include the following:
- Decreased blood flow to the fetus. This can result in low fetal blood and/or oxygen levels;
- Intrauterine Growth Restriction (IUGR). The flow of nutrients decreases, resulting in minimal growth of the fetus;
- Compression of the cord during vaginal delivery. Blocks the flow of blood and oxygen to the fetus;
- A true knot in the cord. This can completely block any blood flow to the fetus, increasing the risk of fetal death;
- Developmental delay. For example, cerebral palsy can result from low blood and oxygen levels (anoxia);
- Stillbirth. Prolonged restriction of blood and oxygen levels can result in death.
A fetus does not breathe air until it is delivered, so its oxygen supply comes from the mother’s blood flowing through the umbilical cord to the fetus. If the cord becomes knotted or compressed, the blood flow becomes restricted, decreasing the amount of blood, nutrients, and oxygen it receives. How tightly compressed the cord is will determine the amount of damage caused to the fetus.
Nuchal cord – diagnosis and treatment:
A nuchal cord can be diagnosed during a uterine ultrasound which is a method that uses sound waves to create images showing the tissues and structures of the fetus and womb. Nuchal cords are not always seen on imaging and may not be apparent until birth.
There are no methods to prevent or treat a nuchal cord. If a nuchal cord is seen on ultrasound, your doctor will continue to monitor the growth of the fetus and the amount of amniotic fluid present. They will also have you track the movements of your baby.
Nuchal cords are common, occurring in about 1 in 4 births, and do not always cause complications to the fetus. How tightly the cord is wrapped will determine the amount of blood and oxygen flow that is restricted to the fetus. If umbilical blood flow becomes compromised, a cesarean section may be required. The majority of nuchal cord cases result in uncomplicated vaginal deliveries.