Every parent of a child with autism wonders what might have caused the disorder. Does it secretly run in the family? Was there a toxic exposure during pregnancy? An infection in early infancy? Was the mother or father too old?
Amy Sawelson Landes of Tarzana, Calif., has asked herself all of these questions, plus one more: Could the fact that she had taken an infertility drug to get pregnant have contributed to her son Ted’s autism? “It was one of the first things I wondered about,” says Landes, who was 37 when Ted was born 18 years ago.
A study presented Wednesday at the International Meeting for Autism Research in Philadelphia provides some of strongest evidence to date that Landes might be onto something. The study, conducted by a team at the Harvard School of Public Health, found that autism was nearly twice as common among the children of women who were treated with the ovulation-inducing drug Clomid and other similar drugs than women who did not suffer from infertility, and the link persisted even after researchers accounted for the women’s age.
Moreover, the association between fertility drugs and autism appeared to strengthen with exposure: the longer women reported being treated for infertility, the higher the chances their child had an autism spectrum disorder (ASD).
A second paper presented at the conference by an Israeli team found an association between autism risk and in vitro fertilization, which also involves the use of drugs that stimulate ovulation. Taken together, the studies add to a growing body of evidence that a history of infertility and treatment for infertility could play a role in causing autism. However, the papers raise more questions than they answer.
The Harvard study was the first to look specifically at Clomid-type drugs and autism. It was a large study involving data from 3,985 women — all of them nurses; 111 reported having a child with autism. However the data was based on questionnaires completed by the women, rather than clinical records, so there was no way to confirm the history or timing of treatment for infertility or autism diagnosis. Nor did researchers have access to information on whether the affected children were born prematurely, whether they were twins or triplets, or whether they had low birth weights.