What causes hypoxic ischemic encephalopathy (HIE)?

A: Hypoxic-ischemic encephalopathy, sometimes referred to as neonatal asphyxia, is a brain injury caused by a lack of oxygen-rich blood in the baby’s brain. HIE can result in infant seizures, difficulty feeding, low muscle tone, limpness, organ dysfunction, and breathing problems. HIE-related brain damage can also lead to other serious conditions, such as cerebral palsy (CP), intraventricular hemorrhages, hydrocephalus, and learning disabilities. On this page, we will focus on the causes and risk factors for HIE. For an overview of HIE, including warning signs, diagnosis, treatment, long-term outcomes, and legal help, please click here.


Hypoxic-ischemic brain injury is caused by a lack of oxygenated blood flow to the brain. Infants are especially susceptible to HIE because their brains are still developing, and a lack of oxygen – even for a short time – can have a serious impact. Oxygen-depriving insults often occur in utero, during labor and delivery, or shortly after birth. Some of the causes and risk factors for neonatal asphyxia/HIE include the following:

  • Nuchal cord: A nuchal cord is a situation in which the umbilical cord is looped or knotted around the baby’s neck. This can cause the cord to become occluded, which will significantly limit the flow of oxygen-rich blood from the mother to the baby. In addition, the nuchal cord can be so tightly wound around the neck that it impinges on the baby’s neck vessels, which leads to decreased oxygen going to the baby’s brain.
  • Umbilical cord prolapse: Prolapse occurs when the umbilical cord travels down through the birth canal in front of or alongside the baby.  When this happens, the cord gets trapped and squeezed between the baby’s head or body and mother’s pelvis. This pressure on the cord can cause blood flow to the baby to slow down or completely stop.  Cord prolapse is an obstetrical emergency, and when it happens, the baby must be delivered immediately, usually by C-section.Umbilical cord prolapse (prolapsed cord)
  • Preeclampsia: Preeclampsia is high blood pressure (hypertension) in a pregnant woman. It can decrease the flow of blood to the baby; one reason this happens is that the high blood pressure causes damage to, or constriction of, the vessels in the placenta through which oxygenated blood normally flows.
  • Post-term pregnancy: Postterm pregnancy is a name for pregnancies that extend beyond the standard 40 weeks (approximately). These pregnancies can  cause HIE as the result of placental deterioration and low amniotic fluid (which can also happen around 37 weeks – not just in postterm pregnancies). Postterm babies may also become too large, making delivery difficult and increasing the risk of HIE.
  • Chorioamnionitis and villitis: Chorioamnionitis is infection and inflammation of the placenta and fetal membranes.  Villitis is infection and inflammation of the part of the placenta that is involved in exchange of gases (such as oxygen) and nutrients, and is associated with chronic chorioamnionitis.  These conditions can cause premature rupture of the membranes (PROM), which can result in serious problems for the baby, including characteristics of prematurity such as underdeveloped lungs. Underdeveloped lungs can lead to oxygen deprivation, fetal distress, and HIE.
  • Meconium aspiration:  Meconium is a mixture of amniotic fluid and the baby’s stool. Sometimes, babies breath this into their lungs around the time of birth. When this happens, the baby can suffer severe respiratory distress and have breathing problems after birth, which can cause or contribute to oxygen deprivation and HIE.
  • Macrosomia and cephalopelvic disproportion (CPD): Macrosomia is a complication in which the baby is large and unable to fit through the mother’s pelvis. CPD is similar, but it is the baby’s head, specifically, that is too large. Labor with macrosomia or CPD is often prolonged or arrested. This is dangerous because the fetus has to withstand more contractions, which limits oxygen flow. Moreover, medical professionals may attempt to pull the baby out using forceps or vacuum extractors. These tools can cause trauma to the head, hemorrhages, and HIE.
  • Placental Abruption: This occurs when the placenta separates from the uterus, which can cause bleeding in the mother and a decreased supply of oxygen-rich blood to the baby.  Placental abruption can also cut off the placenta (and umbilical cord) from the mother’s blood supply, either partially or completely.
  • Uterine Rupture: This is when the uterus (womb) tears open, potentially expelling the unborn baby out of the womb and into the mother’s abdomen.  This most typically happens when there is a prior history of C-section or surgery to the uterus. When the uterus tears, the mother may lose so much blood that the baby becomes oxygen deprived.  Alternatively, the rupture can cause the placenta and cord to be cut off from circulation, which also deprives the baby of oxygen.  Women who have a vaginal birth after C-section (VBAC) are at an increased risk of uterine rupture.
  • Malposition of the baby, such as face presentation, transverse, and breech birth: When a baby is not in the normal position (top of the head exiting the birth canal first), labor can be prolonged, trauma to the head can occur, and the umbilical cord can become prolapsed.  These complications can cause oxygen deprivation in the baby’s brain.  In addition, babies in face presentation can suffer from excessive swelling and fluid build up in their upper airways, which can cause respiratory distress and oxygen deprivation.
  • Delayed emergency C-section: Research shows that when the decision to perform an emergency C-section is made, the baby should usually be delivered in 5 to 18 minutes, depending on the circumstances.  Experts also agree that in other instances, such as a cord prolapse, the baby should be delivered much more quickly.  Often, physicians spend too much time trying to deliver a baby vaginally, and they do not move on to a C-section quickly enough, or they lack the skill or necessary equipment to promptly perform a C-section.  When an indicated C-section is not performed in a timely fashion, the baby is often subject to oxygen-depriving conditions for far too long.
  • Severe maternal hypotension (very low blood pressure): When a mother’s blood pressure is low, the blood flowing from her, through the placenta and umbilical cord to the baby, may be insufficient.  This can deprive the baby of oxygen-rich blood.
  • Intracranial and intraventricular hemorrhage: Hemorrhages (brain bleeds) can occur when there is trauma to the baby’s head.  This can happen during labor and delivery, especially if delivery instruments such as forceps and vacuum extractors are used, or if the baby’s birth position (such as face presentation or breech birth) is mismanaged.  Brain bleeds can cause decreased blood flow and oxygen in the brain.
  • Uterine hyperstimulation (tachysystole): Excessively strong and frequent uterine contractions, called hyperstimulation, can result from improper use of the labor-enhancing drugs Pitocin and Cytotec. Uterine hyperstimulation puts continuous pressure on the vessels in the uterus and placenta, which can impede blood flow to the umbilical cord and baby.  This can lead to severe oxygen deprivation and HIE.

Award-Winning Lawyers Helping Children Affected By HIE Since 1997Reiter & Walsh Cerebral Palsy Attorneys

The lawyers at Reiter & Walsh ABC Law Centers have helped dozens of families affected by hypoxic-ischemic encephalopathy (HIE).  Attorney Jesse Reiter, president of ABC Law Centers, has been focusing solely on birth injury cases for over 28 years, and most of his cases involve hypoxic-ischemic encephalopathy and cerebral palsy.  Partners Jesse Reiter and Rebecca Walsh are currently recognized as two of the best medical malpractice lawyers in America by U.S. News and World Report 2015, which also recognized ABC Law Centers as one of the best medical malpractice law firms in the nation.

If your child experienced a birth injury and now has seizures, HIE, brain damage, cerebral palsy or any other long-term condition, please contact us today.  Our award-winning Michigan hypoxic ischemic encephalopathy (HIE) lawyers are available 24/7 to speak with you.

 

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Related Resources

Video: Michigan Hypoxic Ischemic Encephalopathy (HIE) Lawyers Talk About Birth Asphyxia and HIE

birth injury lawyers discuss nuchal cord and birth asphyxiaWatch a video of Michigan hypoxic ischemic encephalopathy (HIE) lawyers Jesse Reiter and Rebecca Walsh talking about the causes of HIE and the groundbreaking treatment for this condition.