There are a few topic areas in the quite vast autism research landscape that consistently seem to keep cropping up. The possibility of some kind of *association* between pregnancy antidepressant use and risk of offspring autism is one of those areas (see here) as the results published by Dheeraj Rai and colleagues  (open-access) are presented for your attention. I would also draw your attention to an accompanying editorial discussing the Rai findings (see here).
So: "To help to improve the understanding of the association between antidepressant use during pregnancy and autism in offspring, we applied a range of... causal analytical methods on data from a large total population cohort in Stockholm County" was the starting point, as once again one of those very useful Scandinavian registries provided the source study material (indeed, Rai et al are seemingly experts in their analysis of such resources). The added bonus to the Rai study was their attempt to 'unravel' any association between gestational antidepressant exposure and autism from the reason why such medication was being taken in the first place: maternal psychiatric health issues (and whether this variable may in fact account, at least in part, for any association that has previously been identified).
From a starting population approaching three-quarters of a million people, researchers eventually settled on looking at over 250,000 children under 17 years of age (but over 4 years of age "in whom a diagnosis of autism might be less reliable") who were born to over 150,000 mothers. The vast majority of children (239,943 of 254,610) had no history of exposure to antidepressants during pregnancy. The remaining participants were divided up into two groups: one where there was documentation leading to the assumption of exposure to pregnancy antidepressants (n=3342) and one where there was an indication for such exposure ("mothers with a psychiatric disorder") but no recorded use of antidepressants during pregnancy (n=12,325). Researchers summed up how many children were diagnosed with an autism spectrum disorder (ASD) in each group and applied some statistical modelling.
Results: I think it's important to first highlight a statistic that seems to have been missed by many covering the Rai findings: "Of the 238 943 cohort children for whom there was no record of maternal history of psychiatric disorder or antidepressant use during pregnancy, 4889 had autism (2.1%)." That's 2.1% with a diagnosis of autism or ASD; quite a far cry from the 1% [estimate] statistic from just a few years back (at least here in Blighty).
Then: "Exposure to antidepressants during pregnancy was associated with a higher odds of a diagnosis of autism in offspring than exposure to a maternal psychiatric disorder without antidepressants." The authors caution that: "the absolute risk was small, and 4.1% of children exposed to antidepressants in utero had autism compared with 2.9% of those with a maternal history of psychiatric disorder." Further when looking at those children diagnosed with ASD in the groups, authors observed that "autism without intellectual disability" seemed to be over-represented; something also picked up in previous findings from authors on this current paper .
Alongside various opinions on these findings (see here for example), the authors caution about the possible meaning of their results. One obviously has to be quite careful when discussing such data to ensure that an important class of medicines is not unduly vilified. No medicine is however without potential side-effects and appropriate clinical decisions and good medicines management  is key, particularly when pregnancy is included as variable. The authors talk, for example, about how "if a causal link were robustly established, and if no pregnant women took antidepressants during pregnancy, only 2% of autism cases in this population would be prevented." Alongside they [importantly] mention that antidepressant use during pregnancy is not typically just a 'choice' but rather being clinically indicated: depression does not simply disappear when a woman is pregnant. Interestingly too, they mention about how their data "suggest that there is an increased background risk of autism in children of women with psychiatric conditions, regardless of antidepressant treatment." This follows a trend in other areas of psychiatry (see here for example).
Yet again, the call is further research in this area and, quite a few more investigations into the possible hows-and-whys of any association (with medication use and/or maternal psychiatric presentation) is made. I might also suggest that taking into account other childhood conditions such as attention-deficit hyperactivity disorder (ADHD), potentially over-represented when it comes to a diagnosis of autism or ASD, could be another important step forward in light of other preliminary *associations* being made with pregnancy medication history in mind (see here). This also includes looking at any issues associated with timing of potential exposure and/or dose ("Because of small numbers, we were not able to assess trimester specific or dose response effects.").
Insofar as the suggestion that autism without intellectual (learning) disability might be an important phenotype when it comes to any association, subsequent research in this area seemingly fits in well with increasingly vocal calls  to stop using the generic label of autism as a research starting point (see here). Allied to suggestions for more 'bottom-up' research with autism in mind (see here), also coincidentally mentioning "maternal SSRI use during pregnancy" in the context of autism , a future research agenda is seemingly emerging. I might also point out that certain sensitivities need to be kept in mind on the basis of suggestions that an 'environmental exposure' might, in whole or part, be *associated* with a particular type(s) of autism.
All such work - present and future - however needs to be done/presented with care, understanding and minus scaremongering, so as not to unduly alarm pregnant mothers, their families or indeed, the physicians providing their care at such a critical time...
 Rai D. et al. Antidepressants during pregnancy and autism in offspring: population based cohort study. BMJ. 2017; 358: j2811.
 Rai D. et al. Parental depression, maternal antidepressant use during pregnancy, and risk of autism spectrum disorders: population based case-control study. BMJ. 2013 Apr 19;346:f2059.
 Angelotta C. & Wisner KL. Treating Depression during Pregnancy: Are We Asking the Right Questions? Birth Defects Res. 2017 Jul 17;109(12):879-887.
 Waterhouse L. et al. The ASD diagnosis has blocked the discovery of valid biological variation in neurodevelopmental social impairment. Autism Res. 2017 Jul;10(7):1182.
 Unwin LM. et al. A "bottom-up" approach to aetiological research in autism spectrum disorders. Front Hum Neurosci. 2013 Sep 19;7:606.
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