Tuesday, May 6th, 2014
Brain injuries suffered by newborns at the moment of their birth have long been thought to be the result of insufficient oxygen during delivery, with doctors often held responsible by parents. But a new report by a committee of experts in obstetrics, pediatrics, neurology and fetal-maternal medicine has found that the full cause of such injuries, which can result in serious complications, are far more complex than that. The New York Times has more:
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The document, called Neonatal Encephalopathy and Neurologic Outcome, updates a version published in 2003 that focused on oxygen deprivation, or asphyxia, around the time of birth. The new report, which highlights significant advances in diagnosis and treatment in the decade since, was published by the American College of Obstetricians and Gynecologists and the American Academy of Pediatrics. Brain injuries affect about three in 1,000 babies born full-term in the United States, but only half of these cases are linked to oxygen deprivation during labor and delivery, according to the new report. And even in those instances, a problem that occurred long before birth might have exaggerated the effects of a reduced oxygen supply that would have not otherwise caused a lasting brain injury.
According to the 2003 report, fewer than 10 percent of children with cerebral palsy, the most severe such brain injury, showed signs of asphyxia at birth. Unless certain clear-cut symptoms are present then, brain abnormalities are probably not the result of a complication during labor or delivery, the new report states.
Rather, there may be other reasons for neonatal encephalopathy, as brain disorders in full-term newborns are called. These include genetic factors and maternal health problems like hypothyroidism, placental abnormalities, major bleeding during pregnancy, infection of the fetal membranes and a stroke in the baby around the time of birth.
“We know that neonatal encephalopathy has a variety of causes, and we hope this report will enable us to provide more accurate information to affected families and devise better methods of prevention and treatment,” said Dr. Mary E. D’Alton, chief of maternal-fetal medicine at Columbia University Medical Center, who was chairwoman of the task force.
Neonatal encephalopathy is a syndrome of disturbed neurological function that occurs in full-term baby’s first days. It is characterized by impaired consciousness or seizures, often accompanied by breathing difficulties and poor muscle tone and reflexes.
To determine whether an insufficient supply of oxygen and blood during labor and delivery is the likely cause, several factors should be considered together. These include a low Apgar score at 5 and 10 minutes after birth; high acid level (called acidemia) in the umbilical artery; major organ failure; and an M.R.I. scan showing a particular pattern of cerebral injury, according to the new report.
The more of these conditions that are present, the more likely that insufficient oxygen during the birth was responsible for the injury.
Reassuringly, the report pointed out that most infants with low Apgar scores will not develop cerebral palsy. “Even in the presence of significant acidemia, most newborns will be neurologically normal,” the committee said. (A doctor evaluates a newborn on five criteria to arrive at the Apgar score, a fast way to gauge the baby’s well-being.)
The experts noted that “there are multiple potential causal pathways that lead to cerebral palsy in term infants, and the signs and symptoms of neonatal encephalopathy may range from mild to severe, depending on the nature and timing of the brain injury.”
For example, the injury might occur as a result of risk factors at the time of conception or from conditions that develop during pregnancy, like fetal growth retardation or placental lesions.
At this time, there are few effective remedies for those problems, but if certain abnormalities in the fetal heart rate are present when a woman goes into labor, the doctor may be able to prevent a serious brain injury by doing a cesarean delivery.