Study Tracks Pregnant Women With Asthma

Nov. 23, 1999 (Chicago) -- A new study will be looking at the effects of asthma and asthma medications on pregnancy in women with asthma nationwide, so that these women and their doctors will know which may pose a greater risk to the fetus. From the births studied so far, the asthma seems to do the most harm, says Michael Schatz, MD, here at a meeting of asthma and allergy specialists.

Pregnant women with asthma often worry about the safety of their medications. In a culture that promotes a "war on drugs," well-meaning friends and relatives can cause these women to feel guilty about taking asthma therapy. However, physicians usually encourage the women to take these medications, because an asthma episode could harm the fetus, says Schatz, an allergist with Kaiser Permanente in San Diego. He is also the principal investigator of the study and the co-chair of the pregnancy committee for the American College of Allergy, Asthma and Immunology.

The study's initial findings seem to support standard medical advice, he tells WebMD. As more women are added to the study, this advice may have new credibility. If the initial findings are borne out, pregnant women with asthma can keep using their medications with even more assurance that for them, this is good prenatal care, says Schatz.

"[We think] the risk of uncontrolled disease is more than the risk of the medicine," Schatz tells WebMD. "On the other hand, we want to know more about the effect of these medications. ... We don't know everything we'd like to know about the effects of either the disease or the treatment."

The investigators of the study, known as the Registry for Asthmatic and Allergic Pregnant Patients (RAAPP) have documented 182 single births. They wanted to test whether acute asthma episodes or oral steroid medications were linked to low birth weight. All the women in the registry required steroid inhalers to treat their asthma, says Schatz. Investigators also wanted to test whether improved control of asthma leads to better pregnancy outcomes. The registry documents low birth weight, prematurity, and birth anomalies.

So far, six of the infants had low birth weights (3.3%), 15 were preterm, or born before the 37th week of pregnancy (8.2%), and two had birth defects (1.1%). Another 14 were small for gestational age, or weighed in the lowest 10% for the stage of pregnancy in which they were born (7.6%). Schatz tells WebMD that these findings were similar to those in the general population. Although there may have been a higher proportion of low birth-weight babies in these women than would be expected generally, the difference was not statistically significant, he says.

"Our data suggest that acute episodes [of asthma] impair intrauterine growth," Schatz tells WebMD. "This preliminary information is reassuring relative to [users of steroid inhalers], and supports the generalization that there's a risk to uncontrolled asthma." He tells WebMD that RAAPP needs to have 800 births registered in order for the statistics to be valid.

• Pregnant women who have asthma may worry about the safety of their asthma drugs, but most physicians believe that an acute asthma episode is more dangerous to a fetus than the medications taken to control the disease.
• Preliminary research has shown that the incidence of low birth weight, premature delivery, and birth anomalies in newborns is the same in asthmatic women taking oral steroids as in the general population.
• The data has also shown that acute episodes of asthma may be associated with low birth weight.