Here is something destined to create fear and finger-pointing: JAMA Pediatrics has published research that finds a correlation between pregnant women’s use of SSRIs (selective serotonin reuptake inhibitors) — a common group of antidepressants — during the last 2 trimesters of pregnancy, and autism spectrum disorder (ASD). The researchers followed pregnant women and their babies/children in Quebec during a 12-year span. SNRIs (serotonin norepinephrine reuptake inhibitors) did not seem to have an impact.
Specifically, the average percent of children diagnosed with ASD during the study was about the same as the national average, under 1% (.07). Of those children whose mothers had taken SSRIs during the 2nd and 3rd trimesters of pregnancy, the autism rate jumped to 1.22%. Of those exposed only in the first trimester the slight increase was statistically insignificant.
But percentages are deceptive. A JAMA Pediatrics Editorial calculated that SSRI exposure led to “an additional 12 children with ASD (autism spectrum disorder) than otherwise would have been expected out the 2,532 children exposed in utero during the 2nd or 3rd trimester.”
The action of SSRIs might account for why ASD is linked to its use. According to the study:
- SSRIs cross the placental barrier and are found in amniotic fluid
- Serotonin can affect many prenatal and postnatal developments including cell division, neuronal migration (which brings cells into appropriate spatial relationships in the fetal brain), cell differentiation, and synaptogenesis (the formation of synapses in the nervous system).
- SSRIs act by blocking the serotonin transporter, which promotes the accumulation of serotonin in extracellular space.
- The capacity of the brain to synthesize serotonin develops atypically in children with ASD.
- Serotonin receptor 2A binding is altered in the cerebral cortex of children with ASD.
The study did not take into account maternal lifestyles that have been linked to autism, such as smoking or body mass index. In addition, autism is a range. It’s possible SSRI exposure might have only increased what might have been mild autism that could have gone undiagnosed. Many potential triggers for autism are being studied, from genetics to environmental exposures. The answer to what causes ASD may never be fully understood. And even if we understood them, could we control all the variables?
However damning this report looks for SSRI use in late pregnancy, the reality is that the decision to stop SSRIs is not black and white. Depression is a life-threatening condition. For some pregnant women the risk of harm to mental health by stopping SSRIs will outweigh the increased risk of ASD. The decision as to whether to try to stop SSRI use in pregnancy will, as with all health decisions, have to be made by the pregnant woman herself in consultation with her obstetrician and psychiatrist.