During pregnancy, the umbilical cord supplies the baby with oxygen. If the cord is unable to do its job because it is being compressed or otherwise damaged, the consequences can be dire. A disruption in the flow of oxygenated blood to the baby can result in hypoxic-ischemic encephalopathy, cerebral palsy, seizures, intellectual and developmental disabilities, intrauterine growth restriction, and more. There are several cord-related pregnancy complications that restrict oxygen supply to the baby. These include:
- Nuchal Cord
- Umbilical Cord Prolapse
- Short Cord
- True Knot
- Infected or Inflamed Cord
- Vasa Previa
Nuchal Cord & HIE
When the umbilical cord is wrapped one or more times around the baby’s neck, this is called a “nuchal cord.” This condition is actually quite common, with an incidence of about 20-30% of pregnancies. Sometimes the issue resolves itself; other times it persists throughout labor and delivery. Tightly wrapped nuchal cords are dangerous because they can essentially strangle the baby. Also, if the cord becomes compressed against itself or the baby’s neck, this can cut off oxygen supply. In other words, this situation can threaten blood and oxygen flow through the nuchal cord (and indirectly, to the baby), or the cord itself can pose a threat.
Risk Factors for Nuchal Cord Formation:
- Long umbilical cord length
- An especially active fetus
- A large fetus
- Abnormal fetal presentation (e.g. breech)
- Multiples sharing an amniotic sac (cords of twins or other multiples may become tangled around their own necks or their siblings’ necks)
Signs and Diagnosis of Nuchal Cords:
If a baby’s movement slows after 37 weeks gestation, that is a warning sign that there may be a nuchal cord. Another indication is a decreased fetal heart rate.
Nuchal cords are often diagnosed by looking at ultrasound images. It may be necessary for doctors to look at the fetal neck from multiple angles. If an umbilical cord is seen around at least ¾ of the neck, that constitutes a nuchal cord. It is important to note that ultrasounds are not 100% accurate at detecting nuchal cords.
Treatment/Management of Nuchal Cords:
Sometimes, nuchal cords can be managed by a medical professional reaching into the birth canal and maneuvering the cord so that it is no longer wrapped around the baby’s neck. If the cord is wrapped too tightly to do this, it may be clamped and cut after the baby’s head is delivered. In certain cases, an emergency C-section may be necessary.
Cord Prolapse & HIE
In a healthy vaginal birth, the baby exits the cervix first, and the umbilical cord follows the baby down the birth canal. Umbilical cord prolapse is a condition in which the cord emerges before or alongside the baby. This is dangerous because the cord can easily become compressed between the baby’s body and the birth canal, restricting or cutting off oxygen supply to the baby.
Risk Factors for Cord Prolapse:
- Premature rupture of membranes. If the mother’s water breaks too early, when the baby is still positioned high in the uterus, the umbilical cord may make its way into the birth canal before the baby can descend.
- Cord presentation. This is when the umbilical cord is lower in the uterus than the baby, prior to the water breaking. Sometimes in cases of cord presentation, doctors will recommend a planned C-section to avoid the possibility of cord prolapse.
- Long umbilical cord length
- Abnormal fetal presentation (e.g. breech)
- Multiples sharing an amniotic sac (the first baby to be born may drag the cord of another through the birth canal)
- Premature delivery
- Excessive amniotic fluid (this may push the cord down before the baby)
Signs and Diagnosis:
The clearest sign of a cord prolapse is the emergence of the cord prior to the baby. However, this does not always happen, as the cord can also come down the canal alongside the baby. Signs of fetal distress, such as heart rate deceleration, also clue medical professionals into the possibility of cord prolapse.
Treatment/Management of Cord Prolapse:
Sometimes, it is possible for a physician to move the baby away from the cord, possibly with the help of forceps or a vacuum extractor. However, this often fails, and then an emergency C-section delivery is necessary. While preparing the mother for surgery, medical professionals will often opt to push the presenting part of the baby back into the pelvis.
Short Cord & HIE
Unusually long umbilical cords put the baby at risk for a number of complications (see nuchal cord, cord prolapse, and true knot); short cords are also risky, though in different ways. The main issue caused by short cords is placental abruption: the baby’s movement causes the umbilical cord and placenta to become partially or completely detached from the uterus. This leads to bleeding during delivery. The cord itself can also rupture. Both of these issues can reduce or eliminate oxygen supply to the fetus.
Risk Factors for Short Cord:
- Insufficient fetal movement. In a normal pregnancy, as the baby moves around in the womb, the umbilical cord stretches and becomes longer. If the baby is relatively inactive in the first half of pregnancy (typically this is caused by oxygen deprivation), the cord may remain short. Likewise, a short cord may hinder fetal movement.
- First-time pregnancy
- A relatively small fetus
- Mother is of average weight or underweight
Signs and Diagnosis of Short Cord:
Short cord should be suspected if there is low fetal movement; this could both cause and be caused by short cord. Signs of fetal distress should also prompt medical professionals to check for short cord (as well as a number of other birth complications). The length of the umbilical cord can be determined through ultrasound examination. If the cord is short, the mother should be monitored closely for the rest of her pregnancy.
Treatment/Management of Short Cord:
If the cord is extremely short, or there are signs of fetal distress, the mother may be admitted to the hospital for inpatient monitoring prior to delivery. If she is diagnosed with placental abruption or the baby is in fetal distress, then the medical team should quickly prepare the mother for emergency C-section.
True Knot & HIE
The name of this condition, “true knot,” is somewhat self explanatory: it is a knot that forms in the umbilical cord. This can happen when babies move around in the womb. True knot affects about one in 2,000 pregnancies. A true knot becomes especially dangerous when fetal movement stretches the umbilical cord and tightens the knot. This causes vessels in the umbilical cord to become compressed, and limits oxygen supply to the baby.
Risk Factors for True Knot:
- Twins sharing an amniotic sac.
- Excessive amniotic fluid (polyhydramnios)
- A mother who has been pregnant two or more times previously
- A mother who is older than 35
- Long umbilical cord
Signs and Diagnosis of True Knot:
Fetuses connected to an umbilical cord with a true knot may show decreased movement after week 37 of pregnancy. There may also be signs of fetal distress, such as an abnormal heart rate. Usually, diagnosis of a true knot happens through an ultrasound examination. If risk factors for a true knot are present, more frequent ultrasounds are typically indicated.
Treatment/Management of True Knot:
If medical professionals diagnose a true knot, they should closely monitor fetal health. Often, the mother will be admitted to the hospital for observation, and so that emergency intervention can be performed if the knot tightens and the fetus begins to exhibit signs of distress. Usually, this would involve an emergency C-section.
Infected or Inflamed Cord & HIE
Sometimes, maternal infections can spread to the umbilical cord, causing cord inflammation. Chorioamnionitis is an infection that stems from bacteria moving upward through the vagina and into the uterus. It can lead to umbilical cord infection and inflammation, known as funisitis. Sometimes, this is not a severe issue. However, much like other cord problems, funisitis can limit oxygen flow, resulting in serious complications. Chorioamnionitis and funisitis can also increase the chances of preterm labor and neonatal sepsis.
Risk Factors for Funisitis:
- Prolonged labor. This may lead to infection because uterine contractions act as a sort of “suction,” allowing vaginal fluid that may be infected to go up into the uterus.
- Chorioamnionitis is also more common in mothers who have previously given birth.
Signs and Diagnosis of Funisitis:
In extreme cases, there may be signs of fetal distress during labor and delivery. Funisitis can be diagnosed through cord examination and tests of fetal and maternal blood.
Treatment/Management of Funisitis:
If funisitis is very severe, delivery via emergency C-section may be necessary. The infant will also need antibiotic treatment.
Vasa Previa & HIE
In a healthy pregnancy, fetal blood vessels run through the umbilical cord, connecting the infant to the placenta. Vasa previa is a condition in which fetal vessels move out of the umbilical cord’s protection and travel through the membranes that lie across the birth canal. This can happen for one of these two reasons:
- The cord implants in the fetal membranes instead of the placenta, and the fetal vessels need to get to the placenta.
- The placenta is divided into two “lobes” and the vessels must connect the two.
Vasa previa is a dangerous condition because the unprotected fetal vessels may end up rupturing along with the amniotic sac. If this happens, it can lead to massive fetal blood loss.
Risk Factors for Vasa Previa:
- Low-lying placenta or placenta previa (at any point during pregnancy)
- In Vitro Fertilization (IVF) pregnancies
- A mother who has previously had dilation and curettage (D&C) or uterine surgery
Signs and Diagnosis of Vasa Previa:
Vasa previa can be diagnosed through a transvaginal ultrasound with color Doppler. If it is not diagnosed early, it should be suspected if the mother bleeds when her water breaks, or if the baby’s heart rate is abnormal.
Treatment/Management of Vasa Previa:
Once a mother has a vasa previa diagnosis, she should be carefully monitored. Because vasa previa increases the risk of preterm delivery, she should also be given a steroid called betamethasone, which will help the baby’s tissues mature. Between 30-32 weeks of gestation, she should be admitted to the hospital for more frequent testing. Usually, C-section is scheduled for about 35 weeks gestation.
Conclusion: Umbilical Cord Problems and Hypoxic-Ischemic Encephalopathy
On this page, we have covered the main umbilical cord complications that can lead to oxygen deprivation and conditions such as HIE and cerebral palsy. Most of these cord complications are not obvious from the external appearance of the mother; recognizing and diagnosing them requires consideration of risk factors, as well as careful monitoring and examination throughout the pregnancy. If a cord injury occurs and causes hypoxic-ischemic encephalopathy, prompt administration of hypothermia therapy can help lessen the extent of the brain injury. If medical professionals fail to diagnose an umbilical cord problem in a timely fashion, do not respond with appropriate intervention (such as an emergency C-section), or do not provide hypothermia therapy, the child may be entitled to compensation from a medical malpractice suit. Compensation from successful medical malpractice cases helps to defray to cost of specialized care and resources.
The information presented above is intended only to be a general educational resource. It is not intended to be (and should not be interpreted as) medical advice. If you have questions about an umbilical cord problem, please consult with a medical professional.