MedWire News: Pregnant women with poorly controlled asthma face an increased risk of giving birth prematurely, study results show.

The findings emphasise the importance of good asthma control, especially during pregnancy, says the team.

"Concerns regarding potential harmful effect of medications on foetuses often result in inadequate treatment of asthma in pregnancy, whereas risks posed by poorly controlled maternal asthma are often underestimated," Dr Ludmila Bakhireva, from the University of New Mexico in Albuquerque, USA, and colleagues write.

To investigate the effects of maternal asthma control on delivery time and foetal growth, the researchers studied 719 pregnant women with diagnosed asthma.

The women's asthma control during pregnancy was assessed by symptom frequency, interference with daily activities and sleep and reported hospitalisations and unscheduled clinic visits for asthma attacks.

The researchers then compared levels of asthma control with the incidence of preterm delivery, foetal growth restrictions and average birth weight among their children.

They found that women with poor asthma control were significantly more likely to give birth prematurely than those with adequate control. Indeed, 11% of pregnant women with poor asthma control gave birth prematurely, compared with just 6% of those with adequate asthma control.

Similarly, 16% of women who were hospitalised for asthma during pregnancy gave birth prematurely, compared with just over 7% of those with adequate asthma control.

However, asthma control did not appear to influence foetal growth and birth weight.

"This study demonstrates a substantial risk for preterm delivery posed by poorly controlled maternal asthma," Dr Bakhireva and team write in the Annals of Allergy, Asthma and Immunology.

They add that the study also "provides additional evidence regarding the importance of adequate treatment of asthma in pregnancy to maintain optimal asthma control".