A nuchal cord occurs when the umbilical cord wraps around the fetal neck completely or for 360 degrees.
Nuchal cords are common during pregnancy with incidences recorded at around 12 percent at 24–26 weeks, reaching 37 percent at full term.
When an umbilical cord becomes wrapped around the neck, the loop is referred to as the nuchal cord. The term “nuchal” relates to the nape or back of the neck.
The main cause of a nuchal cord is excessive fetal movement.
Other medical reasons why cords may move around the neck of a fetus or may result in loose knots include:
- an abnormally long umbilical cord
- a weak cord structure
- excessive amniotic fluid
- having twins or multiples
One study reported in The Journal of Obstetrics and Gynecology of India found entanglement from longer umbilical cords increased the chances of complications.
It is also possible a nuchal cord is the result of a random event with no explanation.
Nuchal cords are not thought to pose many risks for mother or child with research studies continuing to back this theory.
A nuchal cord may only pose health risks in rare cases. A doctor is likely to monitor a baby during its delivery if they have noticed a nuchal cord in routine ultrasound imaging of the mother’s pregnancy.
Heart rate abnormalities
The most common risk from a nuchal cord is decreased heart rate of the baby during delivery. This is usually the result of reduced oxygen and blood flow through the entangled cord during contractions. Even if there is a decreased heart rate, most babies will still be born healthy.
What is the possibility of stillbirth?
Research has found little or no connection between stillbirth and nuchal cords, although there has been some speculation about the relationship by researchers in Timisoara, Romania.
Their results were noted in the journal Clinical and Experimental Obstetrics and Gynecology and suggested nuchal cord incidents needed to be given more attention. They recommended thorough monitoring of fetal heart rates, during delivery once ultrasounds had revealed nuchal cords. They also suggested cesarean delivery when any distress was noted.
There has been at least one noted case of in utero fetal death at 16 weeks due to a nuchal cord. The 2015 Obstetrics and Gynecology Internationalsame report pointed out the rarity of these incidences and that they tended to occur in the first and second trimesters.
A nuchal cord has no physical symptoms. Unless the fetus has an abnormal heart rate or breathing and oxygen difficulties, a nuchal cord is usually only found during a routine ultrasound scan.
Unless the doctor feels there is a reason to be concerned, no treatments or additional testing are recommended.
Currently, there are no ways to prevent or treat nuchal cords.
A doctor may recommend a cesarean delivery if they feel the fetus is in distress or the mother’s health might be adversely affected by a vaginal delivery. These cases are rare, however.
Most pregnant women will not need to make any special preparations if they find their baby has a nuchal cord. Any concerns they may have should be discussed with their doctor.
Fetal monitoring with ultrasounds can be helpful in preventing complications, but these will not change any delivery outcomes or the potential for complications.
Once labor has started, birthing specialists make no attempts to loosen or unloop nuchal cords, as this could do more harm than good. Moreover, researchers and doctors do not know what effect this would have, and they are careful with intervention.
In general, loose nuchal cords do not warrant a need for cesarean delivery.
Tight nuchal cords occurred in about 6.6 percent of nearly 220,000 births that were analyzed by researchers from the Institute for Healthcare Delivery Research, Salt Lake City, UT. There are only rare cases where nuchal cords pose serious risks during labor and delivery.
A nuchal cord is very common and is rarely a reason for concern.
If a nuchal cord is found during a routine ultrasound, it is monitored for the remainder of the pregnancy, and fetal heart rate is watched carefully during labor and delivery.
There are rare cases of complications, but anytime there is a reason for concern during delivery, a doctor will determine if a cesarean birth or other intervention might be necessary.
If a pregnant mother feels something is not right during her pregnancy, she should speak to her doctor about testing and gain reassurance about her concerns.