How babies’ brains get injured during childbirth

19378572_s

Childbirth is inherently dangerous for babies.

Why? During labor contractions, blood flow to the uterus (and therefore the placenta and baby) is cut off. During each contraction, the baby is, in essence, holding its breath. Most babies tolerate this pretty well, because between contractions the placenta is providing so much oxygen that the baby has a reserve to draw upon during the contractions.

But what happens if the placenta is not functioning optimally? In that case, the baby develops fetal distress. Otherwise healthy babies can tolerate a fair amount of fetal distress. That’s why C-sections done in the early phases of fetal distress produce very healthy, apparently undistressed babies.

It can take a long time for a baby to die of oxygen deprivation in labor, because the baby is usually getting some oxygen, albeit not enough. During that time, if the oxygen deprivation is severe enough, the baby’s brain cells will begin to die because brain cells are extremely sensitive to injury from lack of oxygen. Babies who survive may bear permanent brain injuries. The technical term for this type of brain injury is hypoxic ischemic encephalopathy (HIE).

HIE is often preventable. A new paper by American College of Obstetricians and Gynecologists’ Task Force on Neonatal Encephalopathy, published in this month’s edition of Obstetrics and Gynecology, describes the causes of and treatments for HIE. The paper, Executive Summary: Neonatal Encephalopathy and Neurologic Outcome, Second Edition, is available for free.

This paper should be of particular interest to anyone contemplating homebirth, because the existing scientific evidence shows that in addition to a 3-9X higher increased risk of death at homebirth, there is also an increased risk of injury to the baby during labor (Homebirth increases the risk of a 5 minute Apgar score of zero by nearly 1000%) and an increased risk of HIE (Risk of anoxic brain injury is more than 18 times higher at homebirth).

The paper starts by defining the problem:

Neonatal encephalopathy is a clinically defined syndrome of disturbed neurologic function in the earliest days of life in an infant born at or beyond 35 weeks of gestation, manifested by a subnormal level of consciousness or seizures, and often accompanied by difficulty with initiating and maintaining respiration and depression of tone and reflexes…

How do we know if a specific case of encephalopathy is caused by and event that occurred during labor?

Neonatal Signs Consistent With an Acute Peripartum or Intrapartum Event

A. Apgar Score of Less Than 5 at 5 Minutes and 10 Minutes

1. Low Apgar scores at 5 minutes and 10 minutes clearly confer an increased relative risk of cerebral palsy. The degree of Apgar abnormality at 5 minutes and 10 minutes correlates with the risk of cerebral palsy. However, most infants with low Apgar scores will not develop cerebral palsy.

2. There are many potential causes for low Apgar scores. If the Apgar score at 5 minutes is greater than or equal to 7, it is unlikely that peripartum hypoxia–ischemia played a major role in causing neonatal encephalopathy.

In other words, HIE is often first manifested by a low Apgar score a 5 minutes. Oxygen deprivation can be confirmed by a low pH of blood taken from the umblical cord, and brain injury can be confirmed by damage seen on MRI scans. Oxygen deprivation often causes damages to other organs, too, and these babies can suffer from kidney, liver, heart and intestinal problems due to lack of oxygen during labor.

Sometimes there is an obvious and dramatic cause for fetal oxygen deprivation during labor:

1. A ruptured uterus

2. Severe abruptio placentae

3. Umbilical cord prolapse

4. Amniotic fluid embolus with coincident severe and prolonged maternal hypotension and hypoxemia

5. Maternal cardiovascular collapse

6. Fetal exsanguination from either vasa previa or massive fetomaternal hemorrhage

Anyone planning a homebirth needs to take these possibilities into account. If one of these events occurs, the baby may likely die or be profoundly brain damaged if the event takes place in a hospital. If it happens at homebirth, the risk of brain injury and/or death rises dramatically.

In the absence of a dramatic event, how can we tell that a baby is suffering from oxygen deprivation during labor? Electronic fetal heart rate monitoring.

The patient who presents with a Category I fetal heart rate pattern that converts to Category III as defined by the Eunice Kennedy Shriver National Institute of Child Health and Human Development guidelines is suggestive of a hypoxic–ischemic event.

… Additional fetal heart rate patterns that develop after a Category I fetal heart rate pattern on presentation, which may suggest intrapartum timing of a hypoxic–ischemic event, include tachycardia with recurrent decelerations and persistent minimal variability with recurrent decelerations.

This is critically important. Contrary to the belief of many homebirth advocates, a baby does not need to have a period of prolonged slow heart rate (bradycardia) in order for profound oxygen deprivation to be happening. A bradycardia is often a terminal event; it doesn’t happen until the baby is nearly dead. This is almost certainly what has happened when a mother reports that her baby fell into the homebirth midwife’s hands dead or nearly so even though the heart rate was “normal” throughout labor. Just because the baby’s heart rate is not abnormally slow does not mean that the baby is fine. The signs of fetal distress are often too subtle to be detected by simply listening to the heart rate though it would be glaringly obvious on an electronic fetal monitoring tracing.

Is fetal heart rate monitoring perfect? Hardly, but the problem with monitoring is that it may indicate fetal distress when the baby is not distressed. In contrast, it is extremely reliable when a baby is experiencing oxygen deprivation. In other words, electronic fetal monitoring may lead to unnecessary C-sections, but if your baby is really in distress, it won’t miss it. So when a woman chooses homebirth “to avoid a C-section,” she is making a tradeoff. By avoiding electronic fetal monitoring, she is reducing the chance that she will will have an unnecessary C-section, but she is increasing the chance that her baby will suffocate to death without her midwife having any idea it is happening.

Moreover, the damage to the baby’s brain does not end when the baby is born, even if the baby is then getting enough oxygen, but with head cooling therapy, some of that additional damage can be prevented:

The implementation of hypothermia for the treatment of neonatal encephalopathy is a milestone in neonatal medicine and represents the culmination of research spanning decades that has proved the potential for neural rescue after “perinatal asphyxia.” The recognition that this therapy improves early childhood outcomes has accelerated the pace of investigations to find other brain-oriented treatments. The fact that greater than 40% of neonates undergoing hypothermia treatment still develop adverse neurologic outcomes underscores the need to further understand the underlying processes in neonatal encephalopathy…

Lately, there’s been a lot of discussion in the mainstream media about the increased risk of death at American homebirth. Unfortunately, there has been little or no research on brain injuries resulting from homebirth because, amazingly enough, homebirth midwives don’t bother to track brain injuries. They boast about breastfeeding rates, and ignore brain damage, which gives insight to their priorities.

Brain damage to your baby is a very real consequence of homebirth, and American homebirth midwives can’t be bothered to assess the scale of the problem, let alone prevent or treat it.

Women who choose homebirth are putting their babies brains at risk. How does the baby experience this? Elizabeth Heineman provides a vivid description of what she believes her baby suffered before dying during homebirth:

[The] brain, deprived of oxygen, each cell suffocating, withering into itself, crumpling, collapsing, but still struggling, alerting the nerves that something was terribly wrong. The nerves suddenly plunged into burning acid, receiving the frantic message, send­ing that information in a useless loop back to the very brain that was under siege. The brain screaming in increasing des­peration to the lungs that they should try something, anything. The lungs naively expanding, opening, to pull in relief, to pull in the cool air whose oxygen molecules it will quickly trans­mit to the bluish blood, re-reddening it, re-energizing it, so the blood can rush to the brain, restore it. The lungs instead getting meconium-filled amniotic fluid, choking the blood by transmitting precisely nothing, the blood by now dead but still pumped by the heart that hasn’t yet learned that it is all over, the heart sending the useless blood to the brain cells now wrung dry as they complete the act of withering, crumpling, collaps­ing …

Thinking about homebirth? Think again.