Some Asthma Drugs During Pregnancy May Increase Risk of Autism

A new study reveals that the children of mothers who took a certain asthma medication during pregnancy may face an elevated risk of being diagnosed with autism spectrum disorder.

Drexel University researchers compared birth records over a period of nine years and discovered mothers who took ß-2-andrenergic receptor (B2AR) agonist drugs during pregnancy were 30 percent more likely to be eventually diagnosed with autism spectrum disorder.

B2AR agonist drugs — which include salmetereol and formoterol — are used to relax the bronchial passages in a person’s lungs, providing a release from the constricting nature of asthma.

Nicole Gidaya, Ph.D., a doctoral alum of Drexel’s Dornsife School of Public Health and the lead author of the study explains that the potential impact of most drugs and how they could cause neurodevelopment issues in a fetus is generally understudied.

Gidaya hopes his research will encourage more researchers to explore prescription drug use as a potential autism spectrum disorder risk factor.

Looking at birth records from Denmark dating between 1997 and 2007, researchers determined that children whose mothers took ß-2-andrenergic receptor (B2AR) agonist drugs during pregnancy were 30 percent more likely to be eventually diagnosed with autism spectrum disorder.

The study, “In Utero Exposure to ß-2-Andregenic Receptor Agonist Drugs and Risk for Autism Spectrum Disorders,” appears in the journal Pediatrics.

Craig Newschaffer, Ph.D., professor in the Dornsife School of Public Health, and the director of the A.J. Drexel Autism Institute, is a co-author of the paper and helped conceptualize, design, and acquire data for the study.

“This study adds to a body of recent research suggesting that medications used for certain common health conditions like asthma, when taken in pregnancy, may influence a newborn’s neurodevelopment,” Newschaffer said.

According to the study, B2AR drugs can cross the placenta and reach the fetus, which may have an effect on its developing neurons.

Gidaya and the research team used Denmark’s comprehensive Civil Registration System, to sample from births between Jan. 1, 1996 and Dec. 31 2006. All children in the study could be tied to a biological mother who’d been living in Denmark for at least a year.

As a result, 5,200 children were a part of the case group (those diagnosed with autism spectrum disorder) and 52,000 children were in the control group (those who were not diagnosed with autism spectrum disorder).

The study found that 3.7 percent of children diagnosed with autism spectrum disorder had mothers who took the ß-2-andrenergic receptor (B2AR) agonist drugs during pregnancy. Of children not diagnosed with autism spectrum disorder, 2.9 percent were born to mothers who took the drugs.

Children with mothers who filled their B2AR agonist prescriptions from 90 days before the estimated conception date all the way until their birth date were considered to be exposed to the drug. If a prescription was not filled throughout that entire period, the children were not considered to be exposed.

There was not a marked difference in the odds of a child eventually diagnosed with autism spectrum disease between each trimester (and the 90 days prior to conception). However, the study determined that there was a greater risk when B2AR agonists were taken throughout a pregnancy.

Although the study uncovered the potential risks posed by pre-natal exposure to the drugs, stopping B2AR agonists could also be harmful.

Uncontrolled asthma in pregnancy “has been associated with poor birth outcomes,” according to the study, so completely halting the use of B2AR drugs may not be the perfect solution.

“A challenge here is that the effects of the underlying health conditions, themselves, can also influence developmental outcomes,” Newschaffer said.

“Newly pregnant women taking medication for asthma or other conditions need to work closely with their health care provider to weigh the benefits of continuing medication use against possible risks.”

Additionally, the research team estimated that less than one percent of the autism spectrum disorder diagnoses in the entire population of the study (roughly 628,000 children) could be attributed to B2AR agonist drugs exposure.

Researchers caution that the findings are preliminary as only one other study has considered autism threats associated prenatal B2AR agonist exposure before and it was on a small scale. Nevertheless, the current study is expansive and informative.

Still, “Further research is needed before these results are taken into clinical consideration in the course of prenatal care,” Gidaya said.

Source: Drexel University
Pregnant woman thinking about taking medication photo by shutterstock.