Pregnant women who take antidepressants more likely to have a child with autism, study finds

Researchers stress overall risk remains low and say pregnant women and doctors should not base clinical decisions on any one study

More than 95 per cent of women in the study who took antidepressants during their pregnancy did not have a child with autism (PA Wire)

Women who take antidepressants during pregnancy have a slightly higher chance of giving birth to a child with autism, a new study has found.

Researchers said although it is still too early to pinpoint the cause of the findings, their analysis pointed to the role of the medication, rather than the effects of the mental illness itself.

But they stressed the overall risk remains low and said pregnant women and doctors should not base decisions on whether to use antidepressants on any one study.

Among children exposed to antidepressants in the womb, 4.1 per cent were diagnosed with autism, compared to 2.9 per cent in those whose mothers had a history of a psychiatric disorder, but did not take antidepressants during pregnancy, the scientists found.

Dr Dheeraj Rai, from the University of Bristol, led the research using data from more than 250,000 Swedish children, of whom 5,378 had been diagnosed with autism.

He told The Independent the link was shown to be consistent across a number of statistical analysis methods, such as comparing siblings and balancing results across groups of women who were medication and those who did not.

“We also looked at if the father took antidepressants during the mother’s pregnancy and whether that had any association with childhood autism,” said Dr Rai.

“There was a big difference between the father’s and mother’s data. We didn’t find an association for fathers, only for mothers.”

If a link had been found between fathers’ antidepressant use and autism, it would have allowed the researchers to rule out the possibility that exposure to the medication while in the womb was behind the effect.

Around 3 to 8 per cent of pregnant women in Europe are prescribed antidepressants during pregnancy, according to the research, published in the British Medical Journal.

Unlike other studies carried out into this area, the study differentiated between autism with and without other learning disabilities.

“The associations were found mainly for autism without intellectual disability which includes higher functioning forms of autism such as Asperger syndrome,” said Dr Rai.

“What this suggests is that different forms of autism may have different underlying causes.”

More than 95 per cent of women in the study who took antidepressants during their pregnancy did not have a child with autism.

Even if medication was the cause of the ones who did, it only amounts to 2 per cent of autism cases overall, said the researchers.

Dr Rai said while he was pleased there is a lot of academic debate around the topic, it is one “that can lead to a lot of anxiety” and therefore it is important pregnant women and doctors were not influenced by the results at this stage when making clinical decisions.

“The research evidence is conflicting and different studies have reached different conclusions,” he said. “It’s important to highlight there could be very severe risks of stopping or not taking antidepressants during pregnancy, both to the mother and the foetus.”

Dr Michael Craig, senior lecturer in reproductive and developmental psychology at King’s College London, said it was “important to make clear that these results are not conclusive and the effect size of SSRI [antidepressant] medication on the risk for Autism Spectrum Disorders (ASD) is very small”.

“However, these results cannot be ignored and if the link between SSRIs and ASD is found to be robust then it raises several important issues,” he said.

The study was unable to assess effects over different trimesters, so “it might, for example, be safer to take SSRIs after the first trimester and avoidance of SSRIs in later pregnancy might be safe,” he said.

“Secondly, it is unclear whether other, non-SSRI, antidepressants (e.g. Agomelatine) might be safer in pregnancy.”

Dr James Cusack, director of science for autism research charity Autistica, said pregnant women using anti-depressants “should not be concerned by these results”.

“Previous studies find that anti-depressants do not cause autism and that any link can be explained by factors such as the mother's genetics and increased severity of depression. It seems likely that the link in this study can be explained by the same factors,” he said.

“This study is strengthened by the use of a large health records database which covers the whole of Sweden. Unfortunately the analysis is limited by the amount of data available which means that it cannot explain why an association exists. For that reason the study can only demonstrate an association, it cannot explain the underlying cause of the association.”