Saturday, August 24, 2002
Lack of Oxygen at Birth Not the Cause of Most Newborns' Seizures August 23, 2002 04:05:22 PM PST, HealthScout News
By Adam Marcus HealthScoutNews Reporter
FRIDAY, Aug. 23 (HealthScoutNews) -- Most newborn seizures aren't the result of oxygen starvation during birth, according to a new study.
Johns Hopkins University researchers found that only one of 12 cases of infant seizures out of 22,000 deliveries at that hospital over an 11-year period had brain damage that likely resulted from the birthing process. And 70 percent of seizure patients showed no signs of oxygen deprivation, a leading cause of birth-related neurological injuries.
"We don't know" what's causing the seizures, says Dr. Ernest Graham, a Johns Hopkins ob/gyn and leader of the research team. "It could be a family history of seizures or malformations" of the brain that lead to most of the attacks. But in the vast majority of cases, an oxygen bottleneck -- like a constricting umbilical cord or too much time in the birth canal -- isn't to blame.
A report on the findings appears in the August issue of the Journal of Maternal-Fetal and Neonatal Medicine.
Seizures are the most common sign of brain trouble in early infancy. They affect up to 6 percent of newborns born weighing 3.3 pounds or less, but only 0.2 percent of infants born between 5.5 and 8.8 pounds, or full-term size.
Seizures raise the odds of brain damage in newborns two-to-five times, compared with infants who haven't had the episodes, according to the study. That damage can include cerebral palsy, a devastating neurological disorder.
Some evidence has suggested that as many as half of all newborn seizures are the result of oxygen starvation during labor, Graham said. But another study by the National Institutes of Health found the number to be only 10 percent.
In the latest look at the issue, Graham and his colleagues analyzed roughly 22,000 deliveries at their hospital between 1988 and 1999, of which 13 involved newborns who'd suffered seizures shortly after birth. One was excluded because the child had a chromosome anomaly.
Graham's group compared the 12 infants who'd had seizures with 24 babies of similar gestational age, birth weight and delivery method. They also looked at key measures of newborn health and vigor for both sets of children, including the acid content of the umbilical cord blood and so-called Apgar scores at one minute and five minutes after delivery. The Apgar test is a gauge of how active or lethargic a baby is at birth. A high blood acid content can indicate a lack of oxygen.
Seizure-suffering infants were more likely than the other babies to have poor Apgar scores. Yet, only 30 percent of them had clinically significant blood acid buildup, and only one of the 12 met the American College of Obstetricians and Gynecologists (ACOG) criteria for delivery-related oxygen deprivation and brain injury.
However, Graham noted that the ACOG criteria for labor-related trauma have been criticized as being so strict that they exclude many potential cases.
"They're a little tougher than in the past has been thought" appropriate, agreed Dick Leavitt, director of science information at the March of Dimes, a birth defects group based in White Plains, N.Y. One likely reason, Leavitt said, is professional self-defense.
Still, Leavitt said the new findings agree with the current consensus among neonatologists that most cases of cerebral palsy and related defects have their roots far earlier than delivery.