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Poorly Controlled Maternal Asthma May Increase Risk of Preterm Birth

Asthma can typically be managed with medications and lifestyle modifications. Depending on the extent of the asthma, medications can be used to decrease the inflammation and overexcitability of the airways. Without medications asthma can progress causing wheezing, coughing, chest tightness, or shortness of breath. In severe cases, it may require emergency care or result in death. Some mothers-to-be may be worried about the effect of asthma medications on their unborn babies and therefore stop or reduce their asthma medications.

The University of New Mexico in Albuquerque conducted a study to examine the effects of maternal asthma on the fetus. The study, published in the Annals of Allergy, Asthma, and Immunology , found that poorly controlled maternal asthma posed the highest risks for the developing baby's health.

About the Study

The prospective cohort study reviewed the pregnancies of 791 women with asthma. The researchers defined controlled asthma by the symptom frequency, interference with sleep or activities, and visits to the doctor or emergency room for asthma problems. Based on these characteristics women were divided into adequate control vs inadequate control.

  • Preterm delivery occurred in 6.3% of the controlled group vs. 11.4% of the inadequate control group
  • 16.4% of the woman hospitalized for asthma issues during pregnancy had preterm deliveries
  • Only 7.6% of women that were not hospitalized for asthma issues had preterm births

There was no significant difference between the two groups in terms of intrauterine growth restriction (small baby).

How Does This Affect You?

A prospective cohort does not provide definitive evidence because of the structure of the study. However, it does indicate that poorly controlled asthma may carry a considerable consequence to the health of the fetus. Mothers are often concerned about the effect of asthma medication on the fetus. This study suggests that mothers who used medications to control their asthma had a lower risk of all fetus problems than mothers with uncontrolled asthma.

As with any pregnancy it is important to be medically monitored through the pregnancy. Ask your doctor about any changes you may need to make in your current medication plan. Manage your asthma with the right medication regimen and avoid triggers like allergens, cold temperatures, and flu/cold .




  • Bakhireva LN, Schatz M, Jones KL, Chambers CD. Asthma control during pregnancy and the risk of preterm delivery or impaired fetal growth. Ann Allergy Asthma Immunol . 2008 Aug;101(2):137-43.

Last reviewed November 2008 by Larissa J. Lucas, MD

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