MONDAY, April 3, 2017 (HealthDay News) -- Kids are more likely to develop childhood epilepsy -- a seizure disorder -- if their mothers were overweight or obese early in pregnancy, a new study suggests.
The risk of epilepsy in children goes up as a mother's weight goes up -- reaching as high as 82 percent among kids of severely obese women, the researchers said.
"This means more severe grades of obesity correspond to increasingly higher risk," said study co-author Dr. Eduardo Villamor. He's a professor of epidemiology with the University of Michigan School of Public Health.
However, Dr. Steven Wolf, director of the pediatric epilepsy program at Mount Sinai Health System in New York City, pointed out that the overall risk of childhood epilepsy still remains relatively low, even if a woman is overweight or obese.
It's also important to note that this study wasn't designed to conclusively show a direct cause-and-effect relationship between a pregnant woman's weight and her child's risk of epilepsy.
About 50 million people worldwide have epilepsy, according to the study authors. In 60 percent of those cases, no known cause is found.
The current study included medical data for more than 1.4 million babies born in Sweden between 1997 and 2011. Of all those children, more than 7,500 kids were diagnosed with epilepsy between birth and age 16, the researchers said.
The investigators found that the odds a child would develop epilepsy corresponded to their mom's body mass index (BMI) at around 14 weeks of pregnancy. BMI is a rough estimate of body fat based on a person's height and weight.
A normal BMI is between 18.5 and 24.9. Someone between 25 and 29.9 is considered overweight. Anyone above 30 is classified as obese.
For someone who is 5 feet, 9 inches tall, a BMI of 25 to 29.9 (overweight) means a weight that's between 169 and 202 pounds. A BMI of 30 or more (obesity) is a weight above 202 pounds for someone of that height, the U.S. Centers for Disease Control and Prevention says.
This study also included separate classifications of obesity. From 30 to 34.9 was grade I obesity. From 35 to 39.9 was grade II obesity. And, grade III obesity included anyone with a BMI of 40 or more.
For childhood epilepsy, compared with normal-weight women, the researchers associated:
- 11 percent increased risk with overweight.
- 20 percent increased risk with grade I obesity.
- 30 percent increased risk with grade II obesity.
- 82 percent increased risk with grade III obesity.
Neda Razaz, the study's lead author, said, "Given that overweight and obesity are potentially modifiable risk factors, prevention of obesity in women of reproductive age may be an important public health strategy to reduce the incidence of epilepsy." She's a postdoctoral fellow at the Karolinska Institute in Stockholm, Sweden.
There are several potential ways a mother's excess weight could increase risk of childhood epilepsy, Razaz and Villamor said.
Excess weight increases the risk of preterm birth and birth defects, which in turn increase risk of epilepsy, the researchers said. The baby also is more likely to suffer from trauma or low oxygen levels during birth with an overweight or obese mother. These factors might raise epilepsy risk.
Overweight or obesity also spurs on general inflammation in the mother's body. This could possibly have an effect on their baby's developing brain, Villamor added.
Dr. William Bell is a neurologist with Ohio State University's Wexner Medical Center. He agreed that inflammation could be the culprit behind this increased risk.
"Pregnancy is already an inflammatory state, and so is obesity. When you add those two together, a lot of bad things can happen," Bell said. He wrote an editorial accompanying the new study.
However, Razaz said it's likely that excess weight interacts with other genetic and environmental factors that might contribute to epilepsy risk. These include smoking or drinking, vitamin deficiency, or problems related to a woman's social or economic status.
Wolf said the findings are fascinating, and mothers' weight hasn't been considered a risk factor for childhood epilepsy.
"We take care of a lot of kids with epilepsy, and that's not one of the variables that pop up," Wolf said.
However, Wolf thinks these findings need "a little more validation."
"A study like this makes us pause and stop and think, but my sense is this isn't a significant variable at this moment," he said.
But there are plenty of reasons women thinking about pregnancy might want to control their weight, including pregnancy complications, Wolf and Bell said.
The study was published online April 3 in the journal JAMA Neurology.
SOURCES: Eduardo Villamor, M.D., M.P.H., Dr.PH., professor of epidemiology, University of Michigan School of Public Health; Steven Wolf, M.D., director of pediatric epilepsy program, Mount Sinai Health System, New York City; Neda Razaz, M.P.H., Ph.D., postdoctoral fellow, Karolinska Institute, Stockholm, Sweden; William Bell, M.D., neurologist, Ohio State University's Wexner Medical Center, Columbus, Ohio; April 3, 2017, JAMA Neurology, online