MONDAY, Oct. 3 (HealthDay News) -- Babies born very preterm -- defined as 23 to 31 weeks of gestational age -- are five times more likely than full-term newborns to have epilepsy as an adult, according to a recent study.
The study, based on Swedish medical databases, also found that being born just a few weeks early increased the risk of having the seizure disorder as adults. Babies born as late as 35 to 36 weeks into a pregnancy had a 76 percent higher risk of epilepsy later in life than those born between 37 and 42 weeks, or full-term.
Noting the enormity of the increased risk, one study author said the findings show the importance of "advancing our knowledge" regarding the consequences of preterm birth.
"The magnitude of that effect was surprising," said Dr. Casey Crump, a study author and assistant professor of medicine at Stanford University. The finding "highlights the need to better prevent preterm births, and increases awareness of these effects among survivors of preterm birth, their families and their doctors."
He noted that most people born prematurely live full, "high-quality" lives.
The study is published in the Oct. 4 issue of the journal Neurology.
Epilepsy -- recurrent brain seizures with no obvious cause such as high fever or meningitis -- is the most common neurological disorder, according to background information in the study. It affects more than 50 million children and adults worldwide, the study noted. Seizures occur when a sudden electrical discharge affects the brain, resulting in symptoms ranging from vision changes and staring, to uncontrolled twitching and jerking of the whole body.
The disorder, which often tapers off in adulthood, can be controlled by medications.
In the study, researchers analyzed adult medical records of 630,090 Swedish babies born between 1973 and 1979, looking for hospitalizations for seizures and prescriptions of epilepsy medications from 2005 through 2009. Only drugs used almost exclusively for epilepsy were included as disease indicators.
About 28,000, or 4.4 percent, of those surveyed were born prematurely. Nearly two-thirds of that group were born close to term, at 35 to 36 weeks' gestation.
In the United States, about 13 percent of births are preterm, Crump noted, which "could possibly be due" to maternal risk factors that include infections, other illnesses, high blood pressure, diabetes and excess weight.
Among the adults in the study, 922 were admitted to a hospital during the four-year study period. But 4,405 had been admitted at some earlier point during their lives for treatment of the condition.
The data were adjusted for factors that could affect the outcomes, such as gender, mother's marital status, parental epilepsy and the presence of other illnesses.
An "unexpected" finding, Crump said, was that babies born after more than 43 weeks' gestation received drug prescriptions for epilepsy as adults, suggesting that they also could be at risk. This finding needs "confirmation in other populations," he said.
Preterm infants in the study were more likely to be male, have a twin sibling, be late in the birth order and come from low-income parents with limited education. Their mothers were more likely to be younger than 20 years old, or older than 35. But analyses done after adjusting for these factors showed the same results, the study noted.
The study drew praise from another expert for tracking a large number of infants, or cohort, into adulthood.
"I'm very confident in the results of this study. It is a one of a kind. We don't have many of these kinds of studies here," said Dr. Satyanarayana Gedela, a pediatric neurologist specializing in childhood epilepsy at Children's Hospital in Pittsburgh.
Other studies have suggested a relationship between premature birth and epilepsy in adulthood, but they were small and had mixed results, the study reported.
The researchers conceded that their approach was limited by the need to base gestation periods on mothers reporting their last menstrual periods rather than sonograms, which were not routinely used at the time.
To learn more about preterm birth, visit the U.S. Centers for Disease Control and Prevention.
SOURCES: Casey Crump, M.D., Ph.D., assistant professor, medicine, Stanford University, Stanford, Calif.; Satyanarayana Gedela, M.D., pediatric neurologist, Children's Hospital, Pittsburgh; Oct. 4, 2011, Neurology
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