Conflicting findings have been reported regarding the relationship between epilepsy and birth weight or gestational age, Dr. Yuelian Sun, of the University of Aarhus, Denmark, and colleagues note in the American Journal of Epidemiology.
To investigate further, they studied 1,4 million babies born in Denmark between 1979 and 2002 who were followed up to 24 years of age. Epilepsy cases were identified through the Danish National Hospital Register.
Of the group, 14 334 were sent to hospital with epilepsy at some point over the follow-up period.
The rate of epilepsy diagnosis increased consistently with decreasing gestational age and birth weight. However, the association became weaker as the age at epilepsy diagnosis increased.
Sun's group found that epilepsy in the first year of life was more than five-times more frequent among infants with a gestational age at birth of 22 to 32 weeks compared with those with a gestational age at birth of 39 to 41 weeks.
Similarly, the occurrence rate was five-fold higher among children whose birth weight was less than 2000 grams compared to those whose birth weight was between 3 000 and 3 900 grams.
"The association of low birth weight and short gestational age with the risk of epilepsy was particularly strong within the first five years of life," Sun's team reports, "perhaps because the immature brain is more susceptible to seizures when exposed to risk factors operating during prenatal life than the mature brain is."