Children born to mothers who have previously taken antidepressants are not at an increased risk of developing autism or attention deficit hyperactivity disorder (ADHD), a new study has found.

US researchers compared the health data of over 1,200 children with autism to more than 3,500 children without the condition. Information on the children's mothers was also assessed.

They also compared data on over 1,200 children with ADHD with more than 3,800 children without that condition.

They found no evidence to suggest that prenatal exposure to antidepressants increased the risk of either condition in subsequent offspring.

"The fact that we now have found, in two large case-control studies, no increase in the risk for autism with antidepressant use itself should be very reassuring," commented Dr Roy Perlis, of Massachusetts General Hospital, who was the senior author of this study and a similar study published in 2014.

Previous studies have suggested a link between antidepressants and these two conditions, however this latest research finds that this risk is probably associated with the severity of the mother's depression - which is a known risk factor for conditions like autism - rather than from antidepressant exposure.

The study also found no increased risk linked with antidepressant use during pregnancy.

"While taking any medicine during pregnancy can be a difficult decision, we hope the results of our two papers, which now cover more than 2,500 children with autism and almost 4,000 with ADHD, will provide some reassurance to women concerned about getting treatment for depression or anxiety during pregnancy.

"While there are depression treatments that don't involve medication, for some patients they are not effective, available or preferred. We want women and the clinicians working with them to be as informed as possible when making this decision," Dr Perlis said.

Details of these findings are published in the journal, Translational Psychiatry.