Many studies have examined a potential link between autism and pre-natal exposure to terbutaline, a drug used to treat asthma and pre-term labor. Understanding the most recent research about the potential risks of terbutaline and how it may correlate with autism is important for all expectant mothers.
Changing Understanding About Terbutaline Exposure and Autism
Terbutaline works by relaxing the smooth muscles, helping to open bronchial passageways that become restricted by an asthma attack. Before 2011, doctors also used it in much the same way on the smooth muscles of the uterus, relaxing them to ease the intensity of contractions and stave off pre-term labor. Doctors administered the drug as an injection, through a pump, or in tablet form. It's important to understand that as a treatment for pre-term labor, terbutaline has always been used "off label." This means that it was never approved by the Food and Drug Administration (FDA) or the manufacturer to treat this condition.
Despite this, according to an article published in the journal Obstetrical and Gynecological Survey, more than 260,000 pregnant women received terbutaline each year to reduce their risk of premature delivery. The rising autism rate led many researchers to examine this popular drug as a potential teratogen, or defect-causing agent.
Early Studies Showing a Potential Link
According to the Centers for Disease Control and Prevention, one out of every 88 children in the United States is diagnosed with autism. The dramatic increase in the incidence of the disorder has led to thousands of research studies examining the causes of autism. Prior to 2011, several of these studies focus on the use of terbutaline to treat asthma and pre-term labor in pregnant mothers.
- A 2003 study conducted at Duke University asserted that terbutaline is a neurotoxin. The study went on to say that it could be implicated in neurological disorders in the children of women who received the drug during pregnancy.
- A 2005 study published in the Journal of Child Neurology examined the development of autism in fraternal twins exposed to terbutaline. The study found that it was more likely that both twins would be diagnosed with autism if they were exposed to the drug.
- In 2007, the Journal of Pharmacology and Experimental Therapeutics published a study examining the effects of pre-natal terbutaline exposure in rats. This study found that when rats received a large dose during sensitive periods in their gestation, they displayed autism-like symptoms at birth.
2011 Article Finds No Link
A 2011 article published in the Journal of Obstetrics and Gynecology examined this research into autism and terbutaline and postulated that there was no definitive link between the drug and the developmental disorder. The article takes issue with the methods used in many of the studies, including the high doses given to rat subject, the small sample size in the twin study, and other problems with testing. The article also makes the point that premature delivery is a significant risk factor for developing autism. It contends that many studies have indicated that any environmental exposure linked to ASDs likely occurs in the first trimester, rather than later in pregnancy when pre-term labor is a concern.
FDA Examines Terbutaline Exposure and Autism Risk
In response to a citizen petition from 2008, the FDA examined whether terbutaline could be implicated in autism. The organization's official response to the petition outlines its position on the issue. The FDA concluded that the physical side effects of terbutaline made it too risky to administer to pregnant women. The teratogenic class of the drug was changed to reflect its potential for crossing the placenta and harming the fetus. However, the FDA disagreed that terbutaline could cause autism, stating that the methods used in the testing detracted from the validity of the studies.
2011 FDA Warning Against Use of Terbutaline by Pregnant Mothers
In 2011, the FDA began requiring a black box warning for terbutaline, stating that the drug is not safe for expectant mothers and should not be administered to pregnant women. Although this warning is not related to potential autism risk in the child, it dramatically decreases the chances that pregnant mothers will be prescribed this medication.
What This Means for You
If you're pregnant and at risk for pre-term labor, the new FDA warnings about terbutaline make it unlikely that you'll receive this medication. Although studies have not been able to establish a link between autism and terbutaline, this drug is still unsafe for a developing fetus. As with all medical decisions, it's important to be as informed as possible before consenting to treatment.