Researchers at the Harvard School of Public Health recently discovered a link between the consumption of a common class of infertility drug while pregnant and the birth of autistic children.

The study, presented last Wednesday at the International Meeting for Autism Research in Philadelphia, found that women who had taken ovulation-inducing drugs, either orally or through injections, were at almost twice the risk of giving birth to children who develop autism compared to women who had not taken any fertility drugs. The risk of autism increased with the time the mothers underwent such fertility treatments.

A history of infertility was also found to be associated with autism disorders.

This is the first study to examine the potential relationship of ovulation-inducing drugs and autism, according to Kristen H. Lyall, the study’s lead investigator and a post-doc at the School of Public Health.

Lyall cautioned against jumping to conclusions, as the results are “very preliminary.”

“It would be irresponsible to create anxiety in the thousands of women who are currently pregnant as a result of OID use,” said School of Public Health professor and the study’s senior investigator Alberto Ascherio.

Using data from the Nurses Health Study II, the researchers analyzed almost 4,000 women, looking for women who took OID before their first pregnancy whose children developed autism and adjusting for age of the mothers, pregnancy complications, and other autism risk factors.

Data was obtained only through questionnaires, so the researchers were unable to verify other potential factors such as the subjects’ medical histories, the timing of fertility treatment, or the onset of autism in the children.

Despite the limitations, Lyall said that the link between ovulation inducing drugs, history of infertility, and autism merits further investigation.

Other anecdotal and animal studies have also pointed to increased numbers of autistic children whose mothers had used assisted fertility, said Patricia A. Davis ’84, a pediatrician at Harvard-affiliate Mass. General Hospital who is also conducting research on fertility treatment and autism.

“This a very complex question, and we’re just beginning to get information,” Davis said. “We need to tease out whether [the autism risk] is associated with the age or the mother or father, or genetic risk, etc.”

—Staff writer Helen X. Yang can be reached at hxyang@fas.harvard.edu.