A comprehensive new study has concluded that the use of antidepressants by pregnant women does not increase the risk of intellectual disability for infants.
An international team of researchers from the United States, Canada and Israel looked at data on 179,007 children born in Sweden in the years 2006 and 2007 and linked it up with prescription drug records identifying mothers who took antidepressants.
The results showed that about two per cent of the expectant mothers were on antidepressants at the time of pregnancy, and that, eight years later, 37 of the children from these mothers (0.9 per cent) were diagnosed with an intellectual disability, in comparison to 0.5 per cent within the rest of the population.
According to the study’s authors, the slightly higher rate of disability among children exposed to antidepressant drugs can likely be attributed to the influence of other factors such as the more advanced age of the mothers and fathers as well as the mother’s history of depression.
“We observed a higher relative risk of intellectual disability among offspring born to mothers treated with antidepressants during pregnancy compared with offspring of mothers not treated with antidepressants during pregnancy before adjustment for confounding factors,” say the study’s authors. “However, with incremental adjustment for maternal and paternal confounding factors, this association was gradually attenuated to a statistically nonsignificant relative risk.”
Throughout the general population, intellectual disability —defined as having both an IQ below 70 along with problems with impaired functioning in everyday life— has a prevalence rate of between 0.7 and 2.0 per cent. Its causes can be both genetic, such as chromosomal and hereditary deficiencies, or environmental, most significantly in the form of fetal exposure to infections or toxins.
While some medications like the anti-epileptic and mood-stabilizing sodium valproate have been linked to poor cognitive development and lower IQ in offspring, the scientific consensus on commonly prescribed anti-depressants like SSRIs (selective serotonin reuptake inhibitors) has so far been unclear.
Research has shown that antidepressants pass through the placenta into the fetus’ blood stream, and studies have found links between SSRI use during pregnancy and lower birth weight, reduced time in gestation, reduced fetal head growth and some adverse offspring outcomes including septal heart defects and persistent pulmonary hypertension.
“There has certainly been a lot of reports about associations between taking medication – particularly psychiatric medication -during pregnancy and various outcomes,” said Dr. Alexander Kolevzon, of the Icahn School of Medicine at Mount Sinai in New York City, and study co-author, to Reuters. “If there is a risk, it’s not driven by the medication alone and there are other factors that are contributing. Those may be factors the mother can’t control,” said Kolevzon.
Canada has one of the highest rates of antidepressant use in the developed world. An Organization for Economic Cooperation and Development (OECD) study found that 86 out of 1,000 Canadians take antidepressants. The most prevalent use was found in the United States, where 110 out of 1,000 people take antidepressants.
The new research was published in the journal JAMA Psychiatry.