Ottawa, Canada—Many women with asthma decrease or stop taking their medications during pregnancy, according to a new study detailing why that can be dangerous for both the mother and the unborn child.

The article in the European Respiratory Journal explains why women with asthma who suffer severe symptoms while they are pregnant face higher risks of health problems compared to those with well-controlled asthma.

The large study, which included information on more than 100,000 pregnancies, determined that women with asthma who experienced severe symptoms were more likely to suffer with pregnancy-induced hypertension and preeclampsia. It also documented that babies born to women who suffered asthma attacks appear to be at greater risk of having a low birth weight or being born prematurely or with a congenital abnormality, such as a heart defect or cleft lip.

The study also found that the children’s risk of having asthma and pneumonia was higher in the first 5 years of life.

“Asthma is the most common chronic disease in pregnant women, affecting 8%-13% of pregnant women worldwide,” noted lead author Kawsari Abdullah, PhD, MBBS, a research fellow at the Children’s Hospital of Eastern Ontario Research Institute in Ottawa, Canada. “If asthma is poorly controlled, patients can suffer with severe symptoms such as wheezing, coughing, or feeling breathless or tight-chested. Previous research has shown that one out of every three pregnant women with asthma will suffer severe symptoms, so we need to understand what this means for women and their babies.”

The study team conducted a population cohort study using data from the Ontario asthma surveillance system and population-level health administrative data.

Included in the cohort were 103,424 singleton pregnancies in women with asthma.

Asthma exacerbation (AE) in pregnant women with asthma was defined by the presence at least one of the following criteria: five or more physician visits, or one emergency department visit, or one hospital admission for asthma during pregnancy.

At the same time, ICD9 and ICD10 codes were used to identify pregnancy complications, adverse perinatal outcomes, and early childhood respiratory disorders.

Results indicate that exacerbation in pregnant women with asthma was associated with higher odds of preeclampsia (odds ratio [OR] 1.30; 95% CI, 1.12, 1.51), and pregnancy-induced hypertension (OR 1.17; 95% CI, 1.02, 1.33). In addition, babies had higher odds of low birth weight (OR 1.14; 95% CI, 1.00, 1.31), being preterm (OR 1.14; 95% CI, 1.01, 1.29), and congenital malformations (OR 1.21; 95% CI, 1.05, 1.39).

Furthermore, the researchers write, children born to women with AE during pregnancy had elevated risk of asthma (OR 1.23; 95% CI, 1.13, 1.33) and pneumonia (OR 1.12; 95% CI, 1.03, 1.22) during first 5 years of life.

“AE during pregnancy in women with asthma showed increased risk of pregnancy complications, adverse perinatal outcomes and early childhood respiratory disorders in their children, indicating appropriate asthma management may reduce the risk of adverse health outcomes,” the authors conclude.

“Nearly 40% of pregnant women decrease or stop taking asthma medication because they are worried that it could be harmful to their unborn babies. However, our study indicates that severe asthma symptoms present the greater risk to mother and baby,” added Teresa To, PhD, of The Hospital for Sick Children in Toronto.

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