A new study, published in JAMA Pediatrics, finds a link between antidepressant use during pregnancy and an increased risk of autism in offspring.

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New research shows a link between antidepressants during pregnancy and autism spectrum disorder.

The risk factors for autism spectrum disorder (ASD) are complex, poorly understood and potentially great in number.

Many facets have been studied, but the exact etiology of ASD is a long way from being unravelled.

This current study looks in depth at Canadian births, antidepressant use and their influence on ASD. The results might be considered controversial and are guaranteed to spark debate.

Antidepressant use during pregnancy is already a bone of contention and has been discussed and researched at length. This latest study adds an extra dimension to the conversation.

The question of whether to prescribe antidepressants during pregnancy is a difficult one. There are inferred risks to the unborn child, however, if the prescription is stopped, there are risks for the mother.

As many as 1 in 10 pregnant mothers in the US take antidepressants at some point during the course of their pregnancy.

This high level of prevalence, plus the fact that depression appears to be on the rise, has sparked further research into the implications.

Studies into antidepressant use and pregnancy have so far unearthed a number of associated risks; these include an increased chance of spontaneous abortion, major congenital malformations, premature birth, lower birth weight and pregnancy-induced hypertension.

Other studies have, with various levels of confidence, found links between antidepressant use during pregnancy and a risk of persistent pulmonary hypertension and the possibility of neonatal withdrawal symptoms.

The latest research, led by Prof. Anick Bérard from the University of Montreal and CHU Sainte-Justine children's hospital, adds ASD to this list.

Use of SSRIs significantly linked to increased ASD risk

In short, people with ASD learn, interact, communicate and behave in subtly different ways to the rest of the population.

Each case of ASD is different; some children with ASD may need an incredible amount of support. Other ASD individuals could not be picked out from a crowd, but in certain circumstances, they might struggle to understand or integrate with society.

Because ASD has only been described relatively recently, and the official diagnostic criteria are still in flux, no one knows whether the incidence of ASD is growing, or whether modern parents and clinicians are simply better at spotting it.

Prof. Bérard's study used data from the Quebec Pregnancy Cohort. In total, 145,456 conceptions leading to live births were collated and followed up for 10 years.

For the first time, the investigators took note of not only antidepressant use, but also they marked which trimester the drugs were taken in and, importantly, the class of antidepressants being taken.

The high quality of the Quebec Pregnancy Cohort's data allowed for close control of potentially confounding variables. The team had access to factors including the mother's socioeconomic standing, family history of autism, history of depression, previous births and age at conception.

Prof. Bérard says:

"Amongst all the children in the study, we then identified which children had been diagnosed with a form of autism by looking at hospital records indicating diagnosed childhood autism, atypical autism, Asperger's syndrome, or a pervasive developmental disorder.

Finally, we looked for a statistical association between the two groups, and found a very significant one: an 87% increased risk."

The use of selective serotonin reuptake inhibitors (SSRIs) - a common class of antidepressants - during the second and/or third trimester was significantly associated with an increased risk of ASD.

If the results are to believed, the next natural question for science to tackle is: how do antidepressants affect the unborn child?

Serotonin is known to influence a number of processes in the developing child, before and after birth. It is involved in cell division, neuron migration, cell differentiation and the creation of new synapses.

"Some classes of antidepressants work by inhibiting serotonin (SSRIs and some other antidepressant classes), which will have a negative impact on the ability of the brain to fully develop and adapt in utero," Prof. Bérard explains.

This research adds more information to help guide clinicians and mothers as they decide whether to continue antidepressant treatments into pregnancy. The decision, however, remains an incredibly difficult one.

Medical News Today recently reported on a study linking depression and diabetes to a sedentary pregnancy.