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Why Cesarean Section Has Not Reduced the Incidence of Cerebral Palsy

What Is Cerebral Palsy?

Cerebral palsy is defined by the National Institutes of Health as

a non progressive motor disorder of early infant onset involving one or more limbs, with resulting muscular spasticity or paralysis

Continuous Fetal Heart Rate Monitoring in Labor Does Not Accurately Identify Infants Who Will Develop CP, However, It Has Resulted in Increased Rates of Cesarean Section for “Fetal Distress”

As you can see from the graph below, although the cesarean section rate in “developed countries” has steadily risen since 1970, the incidence of cerebral palsy has not changed.

This is because less than one percent (and perhaps none) of cerebral palsy can be attributable to “birth injury” or “intrapartum asphyxia” (lack of oxygen to the baby during labor).

image

From Nelson, Karin B., Can We Prevent Cerebral Palsy?  30 October 2003 New England Journal of Medicine 349(18): 1765-1768

In fact, the recent surge in elective cesarean section has led to an increase in other neonatal complications.

The incidence of cerebral palsy is about 1.5/1000 births and it has remained fairly stable for the past century, despite the advent of fetal monitoring during labor, increased cesarean deliveries, and improvements in obstetric care. In fact, the incidence of CP seems to be increasing slightly with the increased survival rates of infants born before thirty-two weeks gestation.

Whether or not fetal heart rate monitoring during labor has led to a reduction in cerebral palsy has been researched extensively. The conclusion established by multiple scientific evidence is: Fetal heart rate monitoring during labor does not reduce rates of cerebral palsy, although it does increase the rate of cesarean section. The topic is well summarized by Clark and Hankins

Except in rare instances, cerebral palsy is a developmental event that is unpreventable given our current state of technology. (Reference: Clark and Hankins, March 2003 American Journal of Ob-Gyn 188(3): 628. Temporal and demographic trends in cerebral palsy—Fact and fiction)

A recent study showed that the fetal heart rate tracing during labor failed to identify even  premature infants with brain white matter injury. Reference: Althus et al Can Electronic Fetal Monitoring Identify Preterm Neonates with White Matter Injury March 2005 Obstetrics and Gynecology 105(3):458 (periventricular malacia–an anatomic association with CP–see below)

The weight of evidence on cerebral palsy reveals premature birth is the single strongest risk factor for cerebral palsy

The single way we can most effectively reduce cerebral palsy is to reduce the incidence of preterm birth.

Unfortunately, the incidence of preterm birth has increased from 10% to 12% from 1970 to the present time. The increase in preterm birth rates is largely attributable to multiple gestations produced from artificial reproductive technology (ART), also known as infertility treatment.

Brain

There is so much we do not understand about the human brain and  nerve development that one infant born at 26 weeks may be totally normal, while another may be quadriplegic and severely retarded (have severe cerebral palsy).

What Predisposes Infants to Developing CP?

The four most common conditions found during pregnancies of children who developed cerebral palsy are:

  1. Genetic abnormalities (e.g. birth defects, microcephaly (abnormally small brain), and history of maternal mental retardation)
  2. Birth weight under two thousand grams (2000 g)
  3. Gestational age less than thirty-two weeks
  4. Infection

CP is strongly associated with prematurity; although there are other risk factors:

Risk Factors Preceding Pregnancy

  • Women with long intervals between periods
  • Women with an unusually short (less than 1 year) or long (over three years) intervals between pregnancies
  • Women with recurrent miscarriage or stillbirth (three or more miscarriages or still births)

During Pregnancy

  • Abnormal Placental Vascular Connections (Anastomoses)
    Twin Gestation (C-section prior to onset of labor does not prevent CP in twins)
  • Antepartum Hemorrhage (placental separation/abruption)
    Infection

During Labor/Delivery

  • Inflammation (Infection) of Umbilical cord or amniotic membranes

During early postnatal period (approximately ten percent of CP develops in early childhood)

  • Low gestational age (prematurity)
  • Acidosis (accumulation of lactic acid in the blood from immature lung system, low Apgar scores, asphyxia (lack of oxygen)
  • Intracranial hemorrhage (IVH)

Sciences Notes: What happens to the Brain in People With CP?

Periventricular Malacia is a phenomenon found often in the brains of premature infants in which there is loss of brain matter around the “ventricles” (spinal fluid spaces) as well as within the major nerve mass of the brain. Twenty to 100 percent of infants with ultrasonographic evidence of periventricular malacia have varying degrees of cerebral palsy (CP).
Periventricular malacia is associated with poor myelination (development of nerve insulation protein) and appears to have many causes, most of which occur before or during early pregnancy.

More information on cerebral palsy can be found at the National Institute of Health Cerebral Palsy Page and United Cerebral Palsy (a charitable organization for those with CP)

Questions for You

Are you the parent of a child with CP?

How did you/your family cope with caring for a relative who has CP?

Do you know someone with CP?

Please feel free to comment!

A portion of this post is excerpted from DIY Baby: Your Essential Pregnancy Handbook which you can purchase from Amazon

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{ 3 comments… add one }

  • susana March 10, 2009, 10:19 pm

    Interesting article. Can you clarify for me this statement though:

    In fact, the incidence of CP seems to be increasing slightly with the increased survival rates of infants born before thirty-two weeks gestation.

    How can you say that there is an increase when the graph does not show this? It shows a rise from 1970 to 1990, then a decrease from 1990 to 2000.

    Do you have any idea what the fluctuations could be attributed to? Why were there so many cases in the 70’s? Why the sharp decline between ‘ 75 and ‘ 80?

    thanks,
    Susana

    • Shelley Binkley March 11, 2009, 2:04 pm

      @Susana Thank you for the very interesting comment. The slight trend downward in CP rates since 1990 probably does not reach enough statistical significance to qualify as a decrease in the CP rates. Recent studies (since 2000) have shown a slight uptick in the CP rates in the U.S., thought to be due to iatrogenic prematurity (i.e. increased incidence in preterm birth rates due to assisted reproductive technology or IVF).
      The overall changes in the CP rates since the 1970’s has been attributed by the medical community to improvement in care of early preterm infants (i.e. those born before 28 wks).
      Thanks again for the comment, let’s keep the discussion going!

  • Shelley Binkley October 20, 2013, 3:42 pm

    Unfortunately this is the consequence of a litigious society and a preponderance of trial lawyers.

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