Pregnant women who take antidepressants during the second or third trimester of pregnancy almost doubles the risk that the child will be diagnosed with autism by age seven,according to a recent study.[Photo/Xinhua]

Women who take antidepressants during pregnancy may be at a higher risk of having children with autism, said a study published Monday by the US journal JAMA Pediatrics.

"The variety of causes of autism remain unclear, but studies have shown that both genetics and environment can play a role," said Professor Anick Berard of the University of Montreal, who led the Canadian study of nearly 150,000 pregnancies.

According to her, taking antidepressants during the second or third trimester of pregnancy almost doubles the risk that the child will be diagnosed with autism by age seven, especially if the mother takes selective serotonin reuptake inhibitors, often known by its acronym SSRIs.

Berard and her colleagues used data on all pregnancies and children in Quebec, Canada's largest province, between January 1998 and December 2009.

Of the 145,456 full-term singleton infants born alive, 1,054 were diagnosed with autism, on average at 4.5 years of age. The children were followed up for an average of 6.2 years.

The researchers identified 4,724 infants who were exposed to antidepressants in utero; 4,200 infants were exposed during the first trimester and 2,532 infants were exposed during the second and third trimester, a period critical to a fetus's brain development.

There were 32 infants exposed to antidepressants during the second and third trimester diagnosed with autism and 40 infants exposed during the first trimester diagnosed with autism, according to the results.