The likelihood of a child being diagnosed with autism has been on the rise for decades. In 2006 the estimated rate was one child in 110. In 2008, that number rose to one in 88. Some experts expect that number to rise.
Scientists continue to search for a cause. Now a new study looks at one particular one: a woman's exposure to anti-epilepsy drugs during pregnancy.
Tine Sorensen has lived with epilepsy since she was 15 years old. She is now expecting her second child and continues taking anti-epilepsy medication, including a very low dose of valproate.
"When you are treating pregnant women with medication during pregnancy it's always important to weigh the benefit for the woman with the potential harm for the child," said Dr. Jakob Christensen.
Prenatal exposure to valproate and other anti-epileptic medications has been associated with birth defects and delayed learning in children.
In this report, provided by the Journal of the American Medical Association, Dr. Christensen and his colleagues wanted to determine whether valproate could be associated with an increased risk of autism as well.
Researchers followed more than 500,000 pregnant women in Denmark between 1996 and 2007.
After adjusting for other risk factors such as age of the parents and birth weight, scientists then followed the children to see whether they were diagnosed with autism.
"Among those exposed to valproate during pregnancy there was a three-fold increased risk of autism spectrum disorder and a five-fold increased risk of childhood autism," said Christensen.
The increased risk for developing autism could not be identified for other anti-epileptic drugs.
"So it's always important for pregnant women to discuss with their physician whether they are taking the right medication, or they may change to another type of medication that may fit them better," said Christensen.
It's new information to consider during pregnancy.