Antidepressants and pregnancy: study didn't find they actually cause autism

A new paper published today has reported a small increase in the number of children born with autism in mothers who were using antidepressant medication while pregnant. But the increase was small, and the study did not find one caused the other. So we shouldn’t be changing the way we treat depression during pregnancy.

Previous research has identified a greater than expected presence of psychiatric disorders in the families of children with autism. This could suggest the presence of common underlying genetic factors. Western Australian research also found that prior to the birth of their infant, mothers of children who later developed autism had a higher rate of contact with the mental health system than other mothers. This could have been equally explained by environmental factors such as medication used during pregnancy.

In an attempt to disentangle the potential genetic and environmental factors, and further to previous inconclusive research, this most recent study was conducted on 254,610 people aged 4-17 years living in Stockholm, Sweden from 2001-2011. Given the ever-increasing prevalence of mental health disorders in mothers this is a very important research question.

In order to ensure their findings were as valid and unbiased as possible, the authors adjusted the results for other relevant variables such as parental age and family income and repeated their analysis using several different methods. Their results showed a slightly increased risk (from 2.9% to 4.1%) for mothers who had taken antidepressant medication during pregnancy.

But the paper also showed more than 95% of women who took antidepressants did not have a child with autism.

Interestingly, the risks were observed only for autism without, rather than with, an associated intellectual disability. This shows the findings could have been attributable to genetic factors rather than the effects of the medication, as previous research has found genes appear to be more linked to autism without intellectual disability.

So what should we take from this study?

Clearly, health care providers, pregnant women and those planning a pregnancy will want to know what the results of this new study mean for them. We already know there is a slightly increased risk of autism in the children of women with mental health disorders. Any additional risk from the use of antidepressant medication has been shown in this study to be extremely small.

It’s also important to distinguish between a study that finds a correlation (autism diagnoses increased in the children of mothers who had taken antidepressant medication) and one that finds causation (antidepressants during pregnancy cause autism).

But there is still a need for further research using much larger samples to better investigate the type of antidepressant as well as to take into account the severity of the depression and other aspects of maternal health. Knowing the type of antidepressant would help to understand the mechanism through which any effect may be acting.

In the meantime, it’s extremely important that appropriate clinical management of depression in pregnancy not be compromised in any way by the results of the current study. Pregnant women experiencing depression should stick to their current management plan until we know more.

Helen Leonard has received funding from the NIH in the US.