Hypoxic-Ischemic Encephalopathy (HIE) is a type of brain injury that occurs when a baby’s brain doesn’t receive enough oxygen and blood flow around the time of birth or in early childhood. HIE is not a single-condition diagnosis—it’s the result of events, complications, or a combination of many things. Neonatal HIE falls under the umbrella of Neonatal Encephalopathy.
Understanding the potential causes of HIE is an important part of making sense of your child’s medical journey.
In many cases, a clear cause can be identified like a clear sentinel event. In others, the exact reason may remain uncertain despite thorough investigation. This can be frustrating and emotionally difficult for families. Our goal is to provide clear, compassionate information to help you understand the wide range of factors that may contribute to HIE and support you in navigating the questions that follow.
Sometimes HIE can be caused by various umbilical cord issues. Cord entanglement and compression is rare, but can occur. Sometimes a mother might notice a change in movement during pregnancy. Many of our families had “kick count saves” where movement changed, slowed, or stopped, and they went into Labor and Delivery and their baby was born and resuscitated.
Cord compression can happen intermittently during pregnancy or labor. HIE from too much or too little amniotic fluid, can also affect the umbilical cord leading to HIE.
Whether associated with a placental abruption, or just spontaneously happening, sometimes fetal-maternal hemorrhage is a cause of HIE. This occurs when a bleed happens internally and the baby and mother both lose a significant amount of blood. Sometimes this happens during pregnancy, and other times during labor and delivery.
The placenta is a fascinating and understudied organ. It is very difficult to detect placental issues through standard imaging. There are new research studies underway through the Human Placenta Project to help understand this vital organ in hopes of catching and preventing issues, like those that can lead to HIE.
Some placental issues include:
Infections during pregnancy can cause inflammation and affect placental function, potentially leading to HIE. These include:
Uterine rupture is another cause of HIE. This can happen spontaneously during gestation, due to an external incident such as trauma, during an attempt at a VBAC (vaginal birth after cesarean) where a scar could potentially cause a thinning in the uterus leading to rupture, or as a complication from medications like Pitocin that have a risk for causing Uterine Rupture, but are often used during labor.
It is highly recommended to work with a trained physician, or a high-risk physician, to determine your risk factor for birth options and repeat of issues.
Labor and delivery is a complex process. Many factors come together for a healthy and successful birth. Sometimes, things go well, and other times they do not. Sometimes these are preventable, other times they are not.
Causes such as shoulder dystocia, where a baby gets "stuck" due to a position or a large baby, may or may not be preventable. While imaging can take a best guess at the size of a baby, many times ultrasound is inaccurate and a baby may be larger than originally predicted, or a mother's pelvic girdle is not wide enough to birth a child vaginally.
Location of birth can also increase risk factors. Out of hospital births have a 4x greater incidence rate of HIE and worse adverse outcomes than in-hospital, due to time and resourcing to care. This is especially prevalent in lower resourced areas and countries who do not have access to high-quality maternal and delivery care.
Occasionally, with the above possibilities such as cord compression, placental abruption, etc. some babies need emergency c-sections if there are distress factors that occur. Sometimes these are preventable, and sometimes they are not.
Estimates from the latest validated data sets estimate HIE caused by preventable medical errors, negligence, and malpractice are anywhere between 5-20%. More may be prevented with more consistent CTG monitoring, which is often resource, location and preference-dependent.
Many blood clotting disorders are not detected until something goes wrong to bring them to light, as they are not standard panels and are rare. However, many of our families have found out post-HIE that they are carriers of various blood clotting disorders such as MTHFR. More research is needed to see if there is more of connection and if certain blood tests would better screen for potential issues to the mother and child.
Many families have babies whose HIE was not obvious right away, or who developed HIE in post-birth situations. Some of those include:
Because the combination of a lack of oxygen and lack of blood flow to the brain can cause HIE, some children who experience cardiac arrest due to several different causes, or a near-SIDS event in childhood, can experience HIE.
Sometimes these are near-drownings, sometimes accidental smothering during sleep, and others due to unexpected physical trauma.
There is emerging evidence that genetics can either make a baby more susceptible to HIE, or identified genetic mutations may co-occur with some HIE. In the recent HEAL study, 5% of babies had a genetic mutation, and some additional studies have shown upwards of 20%.
Understanding what babies may not be able to tolerate labor, for instance, due to genetics could lead to better interventions, decrease the incidence and impact of HIE.
You can read more below on the latest research below:
We have comprehensive support programs and services for the whole family, across all outcomes, impacts and ages. We know navigating HIE is filled with many questions and we are here for you.
Connect with families, read inspiring stories, and get helpful resources delivered right to your inbox.
Connect with families, read inspiring stories, and get helpful resources delivered right to your inbox.
