Asthma Management During Pregnancy: How to Benefit Both Mothers and Infants

pregnant woman using asthma inhaler
pregnant woman using asthma inhaler
Although some pregnant women discontinue their asthma medications for fear of fetal drug toxicity, they may be putting their babies at greater risk.

Women with asthma can help their babies as well as themselves with active asthma management during pregnancy. Mounting evidence suggests that adequate asthma control improves outcomes for mothers and their children. Asthma is the most common respiratory ailment in pregnancy, affecting 5% to 8% of pregnant women in the United States.1

Adverse Outcomes for Mothers and Babies

“Poor outcomes like premature birth and pre-eclampsia can result from changes in placental and fetal development that occur very early in pregnancy, during the first trimester,” says Catherine A. Bonham, MD, an instructor of pulmonary medicine at the University of Chicago in Illinois. “Also, as soon as a woman finds out she is pregnant, she may choose to make medication changes that affect her asthma.”

Asthma exacerbations can cause neonatal death, low birth weight, and congenital abnormalities such as cleft lip or palate.1 A retrospective study found that fetal outcomes tended to be sex-associated; female babies tended to be more at risk for low birth weight, while males were more likely to be born prematurely and have higher risk for stillbirth.2 Not surprisingly, children born to mothers with asthma are more likely to develop asthma.1 Approximately one-third of women have asthma exacerbations during pregnancy, and tend to manifest during the second trimester.3

For the mother, asthma is strongly correlated with pre-eclampsia, placental abruption and previa, obstetrical hemorrhage, and higher rates of cesarean delivery.1 Asthma is also associated with non-obstetric comorbidities: a higher incidence of gestational diabetes, increased risk of pulmonary embolism, and viral respiratory infections, notably influenza.1

How Pregnancy Exacerbates Asthma

Pregnancy changes a woman’s cardiac output, stroke volume, and heart rate, all of which may cause asthma exacerbations or new-onset asthma.1 In healthy pregnant women without asthma, there is no change in forced expiratory volume in 1 second (FEV1), a slight increase in forced vital capacity (FVC), and no significant change in FEV1/FVC ratio. Any change in these parameters in pregnant women should be cause for concern.1

During the third trimester, the enlarged uterus compresses the vena cava, resulting in lower venous return.1 Hormonal and mechanical changes in gravid women may spur asthma exacerbations such as nonallergic rhinitis.1,3

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Nearly one-third of women may be inadvertently putting their babies at risk by discontinuing their medications because they fear fetal drug toxicity.4 Although the evidence base for teratogenicity of asthma medications is uneven, a growing body of literature demonstrates the safety of inhaled corticosteroids (ICS) and beta-2 agonists during pregnancy.4

What Clinicians and Mothers Can Do to Improve Outcomes

“My colleagues and I address pregnancy as a part of asthma education for all women of childbearing age, especially women with severe asthma,” says Dr Bonham. “We work to identify triggers and counsel women on trigger avoidance. We also treat asthma aggressively to prevent daily symptoms as well as flares, even if this means going up on asthma medications. Research shows that having good control of daily asthma symptoms and no asthma flares results in the best outcomes for mothers and babies.”

Vicki Clifton, PhD, program leader of Mothers, Babies and Women’s Health at the Mater Research Institute – University of Queensland in South Brisbane, Australia, agrees: “Women with severe asthma should have an assessment from a respiratory physician either prepregnancy or early in gestation. Ideally, multidisciplinary care between obstetrics and respiratory medicine should be considered.”