Findings from a study recently published in the journal Pediatrics indicates that children whose mothers took specific asthma drugs during pregnancy may be at a slightlyincreased risk of autism.

In the study titled “In utero Exposure to β-2-Adrenergic Receptor Agonist Drugs and Risk for Autism Spectrum Disorders,” a research team from Drexel University in Philadelphia found a relationship between the risk of autism and prenatal exposure to beta-agonists drugs, usually prescribed by clinicians to control the symptoms of asthma, including inhaled drugs such as salmeterol (Serevent), formoterol (Foradil) and albuterol.

But women should not simply stop using their asthma medication, either, researchers said. That can cause problems with the baby, too. This should be a personal decision between the pregnant woman and her doctor.

“Uncontrolled asthma in pregnancy has been associated with poor birth outcomes, such as preterm birth, low birth weight, and admission to the neonatal intensive care unit,” the lead researcher of the study, Dr. Nicole Gidaya, said in a news release.

And, preterm delivery and low birth weight have been found to be associated with an increased risk of autism. Dr. Geraldine Dawson, director of the Duke Center for Autism and Brain Development at Duke University in Durham, N.C., agreed, and said in an editorial published with the study that taking beta-agonists during pregnancy has potential benefits and risks for the developing fetus.

With the aim of investigating associations between the use of β-2-adrenergic receptor (B2AR) agonist drugs during pregnancy and the risk for autism spectrum disorders (ASD), researchers used Denmark’s health and population registers in children that were born between 1997 and 2006. A total of 5,200 cases of ASD diagnoses and 52,000 controls without ASD were identified.

The results revealed that 3.7 percent of the ASD cases and 2.9 percent of the controls were exposed to B2ARs during pregnancy, indicating that the use of B2ARs was associated with an increased risk of ASD. This slightly elevated risk was observed with B2AR use during preconception, first trimester, second trimester, and the third trimester, with some evidence that longer B2AR within-pregnancy use was associated with the increased risk.

“It’s important for a woman taking these drugs to talk with her physician and make an individual decision based on her unique circumstances,” Dawson said.

Scientists are still trying to figure out the exact causes of ASD. Beta-agonists come in both short-acting forms and long-acting forms; but, Gidaya said, her study did not differentiate between the two.

Autism is thought to arise from a combination of genetic vulnerability and certain environmental factors. Many genes have been associated with the risk of autism, and the list of environmental risk factors is increasing. According to the advocacy group Autism Speaks, birth complications are among the list of environmental risk factors. So are prenatal exposures to air pollution, certain infections, and some drugs, including the anti-seizure drug valproic acid.

According to Dr. Gidaya, more research is need on the subject, but it’s reasonable to believe that beta-agonists could affect fetal brain development in a way that raises the risk of autism. It is known that when these drugs are given to pregnant lab rats, they can affect fetal nerve cell development.

Autism is a neurodevelopmental disorder characterized by impaired social interaction, verbal and nonverbal communication, and restricted and repetitive behavior. Parents usually notice signs in the first two years of their child’s life. The signs often develop gradually, though some children with autism reach their developmental milestones at a normal pace and then regress.