Researchers have been trying to figure out what causes autism for years. And with some new evidence, they might be a little closer to solving the puzzle.
In a study of more than 145,000 pregnant women, taking antidepressants during pregnancy was linked to an increased risk of autism in the mothers' children.
How much did the risk increase when mothers took antidepressants during their second or third trimesters? Try 87 percent.
And while that's a striking figure, it's worth remembering that many other potential causes of autism have been identified, including older age and depression in moms-to-be. None of those causes have been confirmed.
"The variety of causes of autism remain unclear, but studies have shown that both genetics and environment can play a role," said lead study author Anick Bérard, PhD, a professor in the University of Montreal's Faculty of Pharmacy, in a press release. "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 7, especially if the mother takes selective serotonin reuptake inhibitors, often known by its acronym SSRIs."
SSRIs are one class among several classes of antidepressants. Antidepressants chemically treat depression, a mental health problem the World Health Organization predicts will be the world's second most common cause of death by 2020.
So these medications play a critical role in many patients' health. But Dr. Bérard and colleagues believe they could also be responsible for many cases of autism. Autism refers to a range of a neurodevelopmental disorders marked by trouble with language, communication and socializing. Autism diagnoses have seen a sharp spike in recent years, but many experts attribute this increase to improved diagnosis methods — not necessarily more children with autism.
Among the 145,456 babies born during this study, just over 1,000 were diagnosed with autism at some point during the study follow-up, which was a rough average of six years. Antidepressant exposure in the womb occurred in 4,724 of these pregnancies — with 4,200 exposures in the first trimester and 2,532 in the second or third trimester.
Among those infants exposed to antidepressants in the first trimester, 1 percent were diagnosed with autism. For infants exposed during the second or third trimester, that figure was 1.2 percent.
Overall, compared to pregnancies that didn't involve antidepressant exposure, exposure in the second or third trimester was tied to an 87 percent increased risk of autism.
If you're among the 6 to 10 percent of pregnant women these researchers estimate take antidepressants during pregnancy, you may be tempted to stop your treatment. But not so fast.
According to the Mayo Clinic, "If you have untreated depression, you might not seek optimal prenatal care, eat the healthy foods your baby needs or have the energy to care for yourself. You also might turn to smoking or drinking alcohol. The result could be premature birth, low birth weight or other problems for the baby — and an increased risk of postpartum depression for you, as well as difficulty bonding with the baby."
That's why you should speak to your doctor about the risks and benefits of your current drug regimen and what your options are.
In an editorial about this study, Bryan H. King, MD, MBA, of Seattle Children's Hospital, warned against demonizing any one factor — including antidepressant use during pregnancy — as the definite cause of autism.
"As this literature develops and our list of potential risk factors expands, it is also likely that its complexity will move us even farther from being able to make categorical statements about something being all good or all bad,” Dr. King wrote.
Because these researchers defined antidepressant use as having a prescription for an antidepressant filled during pregnancy, these study results might have been limited. Having a prescription filled doesn't necessarily mean the patient took the drug. But past research found that pregnant women took roughly 94 percent of the drugs they were prescribed, Dr. Bérard and team noted.
The study and editorial were published Dec. 14 in JAMA Pediatrics.
The Canadian Institutes of Health Research and Quebec Training Network in Perinatal Research funded this study. Dr. Bérard served as a consultant in law proceedings involving birth defects and antidepressants.
