NEW YORK (Reuters Health) – Women with inadequately treated asthma during pregnancy are at increased risk for premature delivery, according to findings by the Organization of Teratology Information Specialists (OTIS) Collaborative Research Group.

Medications to treat asthma are often restricted during pregnancy out of concern for potential harm to the fetus, even though there is evidence that severe asthma may affect perinatal outcomes, lead author Dr. Ludmila N. Bakhireva and her associates note in the August issue of the Annals of Allergy, Asthma and Immunology.

To examine the potential adverse effects of poorly controlled asthma, the OTIS investigators studied 719 pregnant women enrolled in their prospective Asthma Medication in Pregnancy Study between 1998 and 2003. The subjects kept track of their medication use, symptom frequency, and interference with daily activities and sleep, as well as hospitalizations and unscheduled clinic visits for asthma exacerbations.

Inadequate asthma control was defined as the presence during the prior 2 weeks of asthma symptoms that interfered with sleep or activity.

The incidence of preterm delivery was significantly higher among subjects with inadequate asthma symptom control during the first 20 weeks of gestation (11.4% vs 6.3%; adjusted odds ratio 1.93, p = 0.02). The incidence of preterm delivery was more than doubled among women hospitalized for asthma during any part of the pregnancy (16.4% vs 7.6% adjusted odds ratio 2.29, p = 0.03).

“The risk of preterm delivery among patients with inadequate asthma control was independent from systemic steroid use,” Dr. Bakhireva, at the University of New Mexico in Albuquerque, and her associates note, indicating that “asthma control is still more important than inherent severity.”

These findings highlight “the need to optimize asthma control and prevent asthma exacerbations