As with many studies, this one doesn't prove anti-depressants cause autism.
But it does show strong evidence that some of them may be linked to a higher risk for the disorder.
The drugs in question are known as SSRIs. They include Prozac, Paxil and Zoloft.
Researchers in Quebec followed nearly 150,000 moms and babies for ten years.
They found a significantly higher risk for autism when women used an SSRI during the second or third trimester.
Still the doctors recognize this could be due to other factors and in some cases the harm of depression during pregnancy can be riskier than medication.
The study is published in JAMA Pediatrics.
Researchers say because anti-depressants are so widely-used, we need to learn more about this potential link.