Asthma can cause serious problems during pregnancy. Pregnant women with asthma are at higher risk of giving birth prematurely, having low-birth-weight babies, or having pre-eclampsia (blood pressure changes) than women without asthma. Because of that, doctors recommend that pregnant women control their asthma medication. But researchers from 19 institutions across the country who studied pregnant women with asthma asked, what if it's the asthma meds that cause the complications?

What the researchers wanted to know: Does taking asthma meds during pregnancy pose a risk to the baby?

What they did: The patients were part of one of two studies by the National Institute of Child Health and Human Development's Maternal Fetal Medicine Units Network. One was an observational study of women with asthma, and the other was a trial comparing two drugs for controlling asthma during pregnancy. In the observational study, 873 women had mild asthma, 814 moderate asthma, and 52 severe asthma, and their doctors decided how to treat their asthma as usual. All 384 women in the drug trial had moderate asthma, and they were randomly assigned to use theophylline or inhaled beclomethasone, which is a corticosteroid.

What they found: Controlling asthma still seems like a good idea: There was no relationship between use of beta-agonists, inhaled steroids, or theophylline and complications such as pre-eclampsia, low birth weight, and premature birth. However, women on oral steroids were more likely to give birth prematurely, even after adjusting for age, smoking, race, insurance status, and about nine other factors that could have influenced the relationship.

What the study means to you: It appears that it's the asthma that causes problems, not the asthma meds, with the apparent exception of oral steroids. That would suggest that medicating asthma is still smart.

Caveats: This is just one study, and just because it didn't find a relationship between drugs and complications doesn't mean that one doesn't exist. For example, there weren't enough women enrolled to find out whether some drugs made congenital defects more likely.

Find out more: The Maternal Fetal Medicine Units Network, which originated the two asthma studies.

Read the article: Schatz, M., et al. "The Relationship of Asthma Medication Use to Perinatal Outcomes." Journal of Allergy and Clinical Immunology. June 2004, Vol. 113, No. 6, pp. 1040-1045.

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