True Knot in Umbilical Cord During Pregnancy

What is a true knot?

“True knots” are knots that form in the baby’s umbilical cord, occurring in roughly 1-2% of all pregnancies (1, 2, 3). Because cord vessels compress when a knot tightens, these knots are very dangerous. A true knot significantly increases the likelihood of fetal death and brain injury from hypoxic-ischemic encephalopathy (HIE).

Knots are detectable via ultrasound, and it is standard of care to test for knots prenatally when certain risk factors exist. Failing to do so is medical negligence. Due to the high risks posed by these knots, it is common to admit the mother to the hospital for close monitoring to prevent sudden fetal distress (when the baby becomes deprived of oxygen). C-sections are often necessary in these cases.

true knot in the umbilical cord

Video: True Knot Explanation

In this video, ABC Law Centers: Birth Injury Lawyers’ previous in-house nurse Andrea Shea discusses what a true knot is and how they can cause hypoxia.

ABC Law Centers: Birth Injury Lawyers includes several in-house medical professionals. Our registered nursing staff provides our legal team with valuable perspectives, experiences, knowledge, and insights into birth injury cases. As experienced medical professionals, they have the necessary knowledge to help us assess each case. Meet our registered nursing staff here.

When are true knots most likely to occur?

A true knot in the umbilical cord is exactly what it sounds like: a knot that forms in the baby’s umbilical cord.

True knots normally form between nine and twelve weeks gestation because that is the period when the amniotic fluid level is very high. There is also evidence that true knots form during labor. These two periods of time are the most likely periods for a true knot to occur (3).

Risk factors for a true knot

True knots are more likely in the instances of:

  • Monoamniotic twins: Identical twins who share the same amniotic sac (3)
  • Polyhydramnios: An excess of amniotic fluid
  • A long umbilical cord
  • Small size fetuses
  • Multiparity: Having two or more previous pregnancies
  • Advanced maternal age: A mother over age 35

Signs of a true knot

Decreased fetal activity after week 37 is the most common symptom of a true knot (2). An abnormal or non-reassuring fetal heart rate will occur when the knot is serious enough to cause a decrease of oxygen to the baby’s brain.

There is nothing a woman can do to prevent a true umbilical cord knot from forming (1). Doctors should monitor the baby closely if there are concerns of decreased fetal activity.

Diagnosing a true knot

Although an abnormal or non-reassuring heart tracing can be indicative of a true knot, an ultrasound examination is the method of choice for diagnosis of a knot (2). When certain risk factors are present, such as the mother being pregnant with monoamniotic twins, it is the standard of care to test for knots prenatally. Specifically, four-dimensional, color Doppler and power Doppler examination are the most important modalities for assessment and diagnosis of a true knot (2).

During delivery, a true knot can be diagnosed by examining the placenta and umbilical cord.

Treating an umbilical cord true knot and preventing HIE

When risk factors for a true knot are present, an ultrasound examination should be performed to determine if there is a knot (3). Knots do not have negative effects in the majority of cases, but in a few cases they can result in intrauterine fetal demise.

For this reason, when a baby has risk factors for a knot, more frequent ultrasounds are required.  When a true knot is diagnosed, strict monitoring of fetal well-being is required during pregnancy and delivery. Often, the physician will admit the mother to the hospital for close and continuous monitoring. True knots can tighten at any time, especially during delivery.

Due to the compression of the cord vessels when a knot tightens, true knots greatly increase the chances of fetal demise and hypoxic-ischemic encephalopathy (HIE) (2). Proper antenatal care must be administered in order to protect the baby from suffering birth injury or fetal demise (2). A C-section delivery is often the safest way to deliver a baby when a true knot and fetal distress are present. Often, a baby must be delivered by cesarean section when a true knot is present, and if the baby is experiencing non-reassuring heart tones, an emergency C-section is usually necessary.

Legal help for children with HIE and injuries from a true knot

If your loved one suffered permanent damage from an umbilical cord complication, we encourage you to contact a law firm with experience in these types of complex medical malpractice cases.

ABC Law Centers: Birth Injury Lawyers was established to focus exclusively on birth injury. Our attorneys and in-house medical staff determine the causes of our clients’ injuries, the prognoses of birth-injured children, and areas of medical negligence. While we’re based in Detroit, Michigan, our attorneys handle cases all over the United States. Please reach out today to learn more. Clients pay nothing throughout the entire legal process unless we win their case.


  1. What to Expect, E. (2018, November 27). Cord Knots During Pregnancy. Retrieved February 2, 2019, from
  2. True Knot of Umbilical Cord. (n.d.). Retrieved February 2, 2019, from
  3. Ikechebelu, J., Eleje, G., & Ofojebe, C. (2014). True umbilical cord knot leading to fetal demise. Annals of medical and health sciences research4(Suppl 2), S155-8.