The large observational study, led by Anick Bérard, Ph.D., professor of perinatal epidemiology at the University of Montreal, found that taking antidepressants — particularly selective serotonin reuptake inhibitors, commonly called SSRIs — during the second or third trimester of pregnancy is associated with an 87 percent increased risk of autism spectrum disorder in children. That headline-provoking number represents a relatively large associated increase in what begins as a small number: Among the pregnancies studied, the rate of diagnosis of autism rose from less than 1 percent to less than 2 percent of children when the mothers were taking antidepressants. The findings were based on all pregnancies in Quebec between January 1998 and December 2009, and included 145,456 pregnancies that resulted in full-term, singleton babies.