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Temporal and demographic trends in cerebral palsy--fact and fiction
Steven L Clark1, Gary D V Hankins
1University of Utah School of Medicine, LDS Hospital, Salt Lake City, USA.
Insights
Cerebral palsy rates in developed nations remain unchanged despite advances in fetal monitoring and cesarean delivery. Current technology cannot prevent most cases of cerebral palsy, which is a developmental event.
Area of Science:
- Neurology
- Obstetrics
- Neonatology
Background:
- Cerebral palsy rates have not declined in developed countries over 30 years.
- Neonatal survival has improved, leading to a hypothesis that improved survival of premature infants masked reduced cerebral palsy in term infants.
Purpose of the Study:
- To evaluate the hypothesis that increased survival of premature, neurologically impaired infants has masked a reduction in cerebral palsy among term infants.
- To analyze the relationship between electronic fetal monitoring, cesarean delivery rates, and cerebral palsy prevalence.
Main Methods:
- Review of the medical literature.
- Demographic analysis of term and preterm birth rates in the United States.
- Separate analysis of cerebral palsy prevalence in term infants.
Main Results:
- Cerebral palsy prevalence has not changed in term infants over 30 years.
- Cerebral palsy rates are similar or lower in underdeveloped countries with limited cesarean delivery access.
- The rise in cerebral palsy among low-birth-weight infants preceded the increase in cesarean sections for fetal distress.
Conclusions:
- The hypothesis is refuted; improved neonatal survival has not masked reduced cerebral palsy.
- Cerebral palsy is largely unpreventable with current technology, often being a developmental event.
- Electronic fetal monitoring and increased cesarean deliveries have not demonstrably reduced cerebral palsy rates.
Abstract:
The rate of cerebral palsy has not decreased in developed countries over the past 30 years, despite the widespread use of electronic fetal heart rate monitoring and a 5-fold increase in the cesarean delivery rate over the same period of time. However, neonatal survival has improved during these decades. These observations have lead to the hypothesis that increased survival of premature, neurologically impaired infants may have masked an actual reduction in cerebral palsy among term infants as a result of the use of electronic monitoring and the avoidance of intrapartum asphyxia. A review of the medical literature, as well as a demographic analysis of term and preterm birth rates in the United States, refutes this hypothesis on four grounds. First, cerebral palsy prevalence has been separately analyzed in term infants and shows no change over 30 years. Second, the prevalence of cerebral palsy is the same or lower in underdeveloped countries than in developed nations; in the former, the availability of emergency cesarean delivery based on electronic monitor data is limited or absent. Third, the increase in prevalence of cerebral palsy among low-birth-weight infants and the increase in cesarean sections based on presumed fetal distress were not simultaneous events-the former preceded the latter by a decade. Improved neonatal survival since the 1980s has been associated with a stable or decreasing rate of neurologic impairment and thus could not have obscured improvement from reduced term asphyxia. Finally, compared with the number of infants born by cesarean section for fetal distress, there are simply not enough infants born in the most vulnerable weight groups to make any impact on even a minimal improvement of outcome in the group delivered by cesarean section for presumed fetal distress. Except in rare instances, cerebral palsy is a developmental event that is unpreventable given our current state of technology.