Children whose mothers took fertility drugs were almost twice as likely to have autism, according to a new study.
The study, conducted by researchers at the Harvard School of Public Health and presented Wednesday at the International Meeting for Autism Research in Philadelphia, found that autism was nearly twice as common among children of women who were treated with the ovulation-inducing medicines than women who did not suffer from infertility.
Researchers asked 111 women taking part in the Nurses' Health Study II who had a child with an autism spectrum disorder about their history of fertility problems and use of ovulation-inducing medicines.
About 34 percent of moms with an autistic child had used fertility drugs compared to about 24 percent of around 3,900 mothers without an autistic child, according to the research. Nearly 47 percent of moms of autistic kids reported infertility, compared to about 33 percent of the other mothers. And, according to the study, the longer women reported being treated for infertility, the higher the chances were that their child had an autism spectrum disorder.
Although many experts cautioned that the study was based on a questionnaire form administered to mothers of children with autism, and that the details of the study have not yet been published, the question about an ostensible link between infertility drugs and autism interested many autism experts.
"This study adds to a growing body of findings suggesting that reproductive assistive technologies are associated with increased risk for less optimal outcomes in babies," said Geraldine Dawson, chief scientific officer of Autism Speaks. "The risk, however, is still relatively small and this should be reassuring to women who are using these drugs."
About 10 percent of women in the United States ages 15 to 44 suffer from infertility, according to the Centers for Disease Control and Prevention. And many of those women choose to undergo various types of infertility treatments such as in vitro fertilization (IVF) or ovulation inducing medications.
Older women are more likely to have fertility problems and to take ovulation-inducing drugs, according to past research. And prior research has shown that older moms are also more likely to have autistic children.
Although researchers took into account women's maternal age, many experts agreed that other stronger associations among mothers using reproductive assistance also may have been a contributing factor to why researchers found a higher number of children with autism.
According to Dr. Max Wiznitzer, a pediatric neurologist at University Hospitals in Cleveland, while there may exist an association between infertility drugs and the development of autism, there may be other explanations to consider. Perhaps factors such as damaged eggs or other environmental causes for infertility could play a role in the number of autism cases among women treated for their infertility.
"Whether it is a cumulative exposure to the infertility drugs, or a reflection of the impact of the cause of the infertility is uncertain," said Wiznitzer.
While there may be an association between IVF and the development of autism, research is not clear whether IVF or other fertility inducing medications cause autism, said Dr. Ernest Krug, a developmental-behavioral pediatrician at William Beaumont Hospitals in Royal Oak, Mich.
"It's good to do these studies, but the problem comes when we try to draw conclusions too quickly," said Krug. "I think we just have to be cautious about telling people that you better not pursue modes of infertility treatments when we just don't know that."
In fact, the complexities of finding associations for autism can span from environmental triggers to numerous identified genes, said Krug. Perhaps infertility treatment may be added to the list of triggers, although it is still too early to tell, he said.
"[Autism is] a very complex area," said Krug. "There needs to be more research in this area before definite conclusions can be drawn."