Using antidepressants during pregnancy greatly increases the risk of autism, according to research published in the journal JAMA Pediatrics.
Professor Anick Bérard, an expert in pharmaceutical safety during pregnancy, led the study at the University of Montreal. Her team reviewed data covering 145,000 children from conception to the age of ten. ‘The variety of causes of autism remain unclear, but studies have shown that both genetics and environment can play a role,’ she said.
‘Our study has established that taking antidepressants during the second or third trimester of pregnancy almost doubles the risk that the child will be diagnosed with autism by age seven, especially if the mother takes selective serotonin reuptake inhibitors, often known by its acronym SSRIs.’
The level of detail included in the data allowed the researchers to assess the specific impact of the antidepressant drugs, and to separate it from other factors such as genetic predisposition, maternal age and depression.
Bérard said: ‘We defined exposure to antidepressants as the mother having had one or more prescription for antidepressants filled during the second or third trimester of the pregnancy. This period was chosen as the infant’s critical brain development occurs during this time.’
‘Among 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 per cent increased risk.’
The researchers say between six and ten per cent of pregnant women are currently being treated for depression with antidepressants.
The prevalence of autism in children has increased from four in 10,000 in 1966 to 100 in 10,000 today. This increase is partly due to better detection, but researchers believe that environmental factors also play a part.
‘It is biologically plausible that antidepressants are causing autism if used at the time of brain development in the womb, as serotonin is involved in numerous pre- and postnatal developmental processes, including cell division, the migration of neuros, cell differentiation and synaptogenesis — the creation of links between brain cells. 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.’