Researchers compared the use of antidepressants among mothers of children with and without ASD. They found that those who had taken selective serotonin reuptake inhibitors (SSRIs) were more than twice as likely to have a child with an ASD diagnosis.
Autism spectrum disorder was uncommon in both groups, and the finding does not prove that SSRI use directly contributed to the children's ASD.
"This is the first study that has shown a possible association between SSRI use and autism and the findings should be considered preliminary," study researcher Lisa A. Croen, PhD, tells WebMD, adding that more research is needed to confirm an association.
WebMD called Pfizer and GlaxoSmithKline, makers of some of the SSRI antidepressants, for comment on the study. Pfizer did not respond before publication time. A spokeswoman for GlaxoSmithKline said the company would not comment because it had not yet had the opportunity to review the new study.
Typically diagnosed in early childhood, autism spectrum disorder is characterized by problems with social interaction, verbal and nonverbal communication, and repetitive behaviors or interests.
Autism spectrum disorders include autism, Asperger's syndrome, and pervasive developmental disorder not otherwise specified.
There has been a huge increase in the diagnosis of autism and related disorders in recent decades. While increased understanding and diagnosis of these conditions may explain the increase, there is also concern that as-yet unidentified environmental influences may be causing more children to develop ASD.
Antidepressant use among women in their childbearing years, especially use of SSRIs, has also increased dramatically in recent decades.
In an effort to investigate whether fetal exposure to antidepressants contributes to ASD risk, Croen and colleagues with the research arm of the California-based managed care group Kaiser Permanente examined the medical records of around 300 children with ASD and their mothers.
These records were compared to those of just over 1,500 children without an autism spectrum disorder.
Twenty mothers of children with ASD (6.7%) and 50 mothers of children without ASD (3.35%) had at least one prescription for an antidepressant in the year prior to giving birth.
Seventy-five percent of those mothers of children with ASD took SSRIs, either alone or with other types of antidepressants. Prescribed SSRIs noted in the study included fluoxetine (Prozac), fluvoxamine (Luvox), paroxetine (Paxil), and sertraline (Zoloft).
When compared with women who did not take antidepressants during pregnancy, those who had been prescribed SSRIs were more than twice as likely to have a child diagnosed with ASD.
The association was not seen with other types of antidepressants, but this may be because so few women took non-SSRI drugs.
The study, which was funded in part by the CDC, is published online in the Archives of General Psychiatry.
Depression During Pregnancy
Between 14% and 23% of women experience depression symptoms during pregnancy, according to the American Congress of Obstetricians and Gynecologists (ACOG).
University of Pittsburgh Medical Center assistant professor of psychiatry Dorothy Sit, MD, tells WebMD that women taking antidepressants should never stop taking them without talking to their doctors.
"This study is intriguing, but it does not establish a direct link between SSRI use and autism," she says. "We would need to study this in much greater detail to do this."
The Kaiser Permanente researchers conclude that even if the association is confirmed, SSRI exposure is not likely to be a major risk factor for autism and related disorders.
Tracy Flanagan, MD, who is director of women's health for Kaiser Permanente Northern California, says maternal depression itself may be an unrecognized risk factor for autism. In the study, the researchers found no link between a history of depression or other mental health disorder and ASD.
She adds that decisions about treatment must be made on a case-by-case basis by the patient, her ob-gyn, and her psychiatrist.
"A woman who has battled depression for many years and has a history of relapsing when she stops drug treatments is very different from a woman who had a single incidence of depression and is doing great," she says.