A new study conducted by University of Montreal researchers found that using antidepressants during pregnancy increases the risk of the child developing autism by 87 percent. The research examined data covering 145,456 pregnancies and was conducted by Professor Anick Bérard, a renowned expert in the field of pharmaceutical safety during pregnancy.

"The variety of causes of autism remain unclear, but studies have shown that both genetics and environment can play a role," she said in a press release. "Our study has established that taking antidepressants during the second or third trimester of pregnancy almost doubles the risk that the child will be diagnosed with autism by age 7, especially if the mother takes selective serotonin reuptake inhibitors, often known by its acronym SSRIs."

Using data from 145,456 children from their conception up to the age of 10, the scientists examined a variety of factors, including the mother's antidepressant use, the child's eventual autism diagnosis, family history, maternal age and socio-economic factors.

"We defined exposure to antidepressants as the mother having had one or more prescription for antidepressants filled during the second or third trimester of the pregnancy," said Bérard. "This period was chosen as the infant's critical brain development occurs during this time."

"Amongst all the children in the study, we then identified which children had been diagnosed with a form of autism by looking at hospital records indicating diagnosed childhood autism, atypical autism, Asperger's syndrome, or a pervasive developmental disorder. Finally, we looked for a statistical association between the two groups, and found a very significant one: an 87 percent increased risk," she said.

The findings are important due to the fact that six to 10 percent of pregnant women are treating their depression with antidepressants.

The study was published in the Dec. 14 issue of JAMA Pediatrics.