Infertility and Autism Risk
Does being treated for infertility raise the risk that your child will have an autism spectrum disorder? A number of mothers I have interviewed have voiced this concern. Now two new studies–one that looks at in vitro fertilization and the other at ovulation-stimulating drugs like Clomid–suggest that it may be so. These are preliminary studies but provocative.
A study presented at the International Meeting for Autism Research in Philadelphia on May 19 found that autism was nearly twice as common among the children of women who were treated with Clomid-type drugs than women who did not suffer from infertility (4% vs 2%), and the link persisted even after researchers accounted for the women’s age.
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. The study looked at 564 children with ASD, who had come to an autism center for in-depth evaluation. It found that 10.2% of the children were the product of IVF, much higher than the rate in the general population of Israel, which is 3.5%.
These studies are far from definitive. The drug treatment study, for example, while based on a large sample of nearly 4,000 nurses, drew its data from questionnaires 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.
“Preterm delivery, low birth weight, twinning and maternal age are all associated with infertility treatment and they are all associated with the risk of autism. We need to understand how to tease these factors apart,” observes Lisa Croen, senior research scientist with Kaiser Permanente in Oakland, Calif., and director of its Autism Research Program, who was not involved in the study.
The IVF study was was even more preliminary and drawn from what researchers call “a sample of convenience.”
Still, it’s interesting to think about how IVF or ovulation promoting drugs might increase the risk of autism. Do the hormones used in fertility treatments cross the blood-brain barrier and affect fetal development? Might the the quality of the eggs the drugs stimulate to ripen be sub-par? Does the growth medium used in IVF procedures sometimes harm the fetus (there’s some evidence for this in animal studies.)? Could there be something about infertility itself that also somehow ups the odds for autism? No one has the answers at this point.