Six to ten percent of pregnant women are currently being treated for depression with antidepressants. Women who stop taking their antidepressants during pregnancy risk relapsing into their depression. So, women with depression often continue taking the medication through this time. In the U.S., the percentage of pregnant women using antidepressants increased from 5.7 percent in 1999 to 13.3 percent in 2003. Although stopping the medication can harm the mother, the use of antidepressants during pregnancy is controversial. Taking the drugs during pregnancy can lead to many complications. For example, it has been linked to neonatal withdrawal, premature birth, and spontaneous abortion.
Now, a study shows children of mothers who take antidepressants during the second or third trimester have an 87 percent increased risk of being diagnosed with autism spectrum disorder by the time they are 7-years-old. The increased risk was observed with the use of selective serotonin reuptake inhibitors (SSRIs), such as Paxil, Prozac, and Zoloft. The researchers did not find there was an increased risk of autism in children of women took SSRIs only during the first trimester. In the study, 0.72 percent of all the children were diagnosed with autism. On average, the child was diagnosed at 4.5-years old.
The scientists reviewed data on 145,456 pregnancies. The data, which came from Quebec Pregnancy Cohort, tracked each child from the time of conception to age 10. It provided information on the mother’s use of antidepressant and the child’s autism diagnosis. It additionally provided details that allowed the team to figure out the specific impact of the antidepressant. For example, the researchers were able to take family history and maternal age into consideration.
"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," said Anick Bérard, an internationally renowned expert in the fields of pharmaceutical safety during pregnancy. The researchers chose to study the second and third trimester because it is when the infant's critical brain development occurs. "Amongst 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 percent increased risk."
The prevalence of autism is growing, increasing from 4 in 10,000 children in 1966 to 100 in 10,000 today. The increase could be due to the widening criteria for diagnosis. However, there are many other factors, such as environmental factors, that could also explain the increase.
"It is biologically plausible that anti-depressants 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 neurons, cell differentiation and synaptogenesis - the creation of links between brain cells," Bérard said. "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."
Depression will be the second leading cause of death by 2020, according to The World Health Organization. Thus, one could assume that antidepressants will remain widely prescribed, even during pregnancy. "Uncovering the outcomes of these drugs is a public health priority,” Bérard said.
The study was published today, December 14, in Jama Pediatrics
Source: press release via Université de Montréa
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, full study via Jama Pediatrics