The Hopkins study, of nearly 22,000 infants born over an 11-year period, found that only one of 12 babies born with seizures met the American College of Obstetrics and Gynecology's criteria for neurological disease linked to the birthing process: a low Apgar score (a measure of newborns' health that identifies those in need of resuscitation) five minutes after birth, and a high level of acid in the umbilical cord - a measure of oxygen deficiency. Seventy percent of the newborns with seizures had no evidence of acidity in the umbilical cord, a finding that argues against the birthing process as the cause of neurological problems.
The study is published in the August issue of the Journal of Maternal-Fetal and Neonatal Medicine. Seizures, the most common and distinctive signal of neurologic problems in the first month of life, affect as many as 6 percent of babies born weighing less than 3.3 pounds, and 0.2 percent of babies weighing 5.5 to 8.8 pounds.
For the current study, Graham and colleagues examined patient records from all babies born at Hopkins between 1988 and 1999. They identified each infant diagnosed with seizures and compared that baby's delivery with a control group composed of the next two healthy babies that were delivered by the same route, at the same age and with similar birthweight. Researchers looked at the babies' Apgar scores at one and five minutes after birth, and reviewed their umbilical cord acid levels.
Of the 13 infants who had seizures, one had abnormal chromosomes and was excluded from further study. The remaining dozen were delivered at an average gestational age of 35 weeks; four were premature. The average birth weight was 2,684 grams (5.9 pounds), compared with 2,745 grams (6 pounds) among the control group. The eight full-term babies with seizures had an average hospital stay of 11.6 days, compared with 2.5 days among healthy babies. Two babies born with seizures died in infancy. Among all babies in the study groups, 83 percent were delivered vaginally and 17 percent by cesarean. There were no significant differences between case and control groups in terms of maternal age or race.
Among the babies with seizures, six (50 percent) had low Apgar scores one minute after birth and four (33 percent) had low Apgar scores five minutes after birth. By comparison, seven of the 24 healthy babies (29 percent) had low Apgar scores one minute after birth, and four (17 percent) had low scores five minutes after birth. Three of the 10 seizure babies whose acid levels were measured showed high acidity, of whom only one also had a low Apgar score five minutes after birth.
"In conclusion, while some have claimed that oxygen deficiency during birth is associated with most cases of neonatal seizures, our findings do not support this," Graham says.
Study co-authors were Cynthia J. Holcroft, M.D., and Karin J. Blakemore, M.D.
Graham, E.M. et al, "Evidence of Intrapartum Hypoxia-Ischemia Is Not Present in the Majority of Cases of Neonatal Seizures," Journal of Maternal-Fetal and Neonatal Medicine, August 2002, Vol. 12, No. 2, pages 123-127.
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