Asthma and Autism: Is There a Link?



AutismBy Laurie Ross 

Recent medical news headlines linked the use of some asthma medications during pregnancy with increased risk of autism in children. The stories cited a study in the February 2016 issue of Pediatrics. The drugs in question are beta2-agonist bronchodilators (called B2AR agonists in the study), which treat the noisy symptoms of asthma: coughing, wheezing and shortness of breath.

They are life-saving medications for those with asthma, which makes the study findings particularly concerning for women. Will a pregnant woman have to choose between breathing and preventing her child from autism?

Not so fast, say leading asthma specialists at the American College of Allergy, Asthma and Immunology (ACAAI). There’s long been speculation about links between asthma and autism, but let’s look at the facts, not the flashy headlines.

Researchers at Drexel University School of Public Health cited previous research that points to the effect of beta agonists on fetal brain development. Seeking to study autism in particular, they reviewed 10 years of records involving Danish children with autism spectrum disorders (ASD), comparing them with a control group without ASD. They found that 3.7% of the autistic children and 2.9% of the control group were born to women who had used beta2-agonists during pregnancy.

Their conclusion: “Our results suggest that exposure to B2AR agonist during the prenatal period was associated with increase in risk for ASD.” They also point out that the increased risk is small: “Less than 1% of ASD cases in the population can be attributed to prenatal B2AR agonist drug exposure.”

A careful reading of the study and knowledge of asthma medication brings up several points to consider:

  • The data about medication use was based on prescriptions filled – specifically, whether the woman had filled at least one inhaled beta-agonist prescription during her pregnancy. The study did not measure actual use of the medication, nor did it differentiate between different varieties of beta-agonists, which include quick-relief albuterol and levalbuterol as well as long-acting beta-agonists like salmeterol and formoterol. Each has its own mechanism of action and effect on the blood and body.
  • A retrospective study like this looks at association among facts, not cause and effect, and it is extremely difficult to control for different factors.
  • A woman with asthma who fills a prescription for a beta-agonist medication can be assumed to be experiencing some difficulty breathing – which could affect her oxygen levels and therefore that of the placenta and the baby.
  • The study was not able to look at environmental conditions that might affect the risk of autism while also triggering asthma symptoms that require medication.
  • Any possible link between beta-agonists and autism supports the need for NIH Guidelines-level care, which seek to minimize the use of beta-agonists among all patients.

Stephen Tilles, MD, president-elect of the ACAAI and editor of AllergyWatch, warns women and their healthcare providers to keep the findings in perspective.

“It’s important to remember that asthma can be dangerous, especially in pregnancy when it can harm both the mother and the fetus,” Dr. Tilles says. “This single study from Drexel provides preliminary epidemiological data supporting a hypothesis that is interesting, but as yet is unconvincing.

“Therefore, while we wait for more data to emerge about ASD and beta agonists, it is imperative that we not alter our approach to managing asthma in pregnancy.”