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Poor asthma control in pregnancy is thought to be due to mechanical or hormonal changes, or because expectant mothers stop taking asthma medications due to concerns about foetal health.¹ The question is, how can clinicians manage asthma in pregnant women for the best outcomes for both mother and child? The answer lies in carefully selecting available asthma management tools to achieve good symptom control while simultaneously easing the mental strain that taking medication can cause pregnant women.

What’s the risk?

Asthma control is often reduced during pregnancy because symptoms worsen in around a third of cases. For the most affected, exacerbations are common, particularly in the second trimester. Exacerbations and poor symptom control are associated with worse outcomes for both mother (pre-eclampsia) and baby (pre-term delivery, low birthweight and increased perinatal mortality). However, the Global Initiative for Asthma (GINA) points out that when asthma is well controlled, there is little or no increased risk of complications. In fact, the benefits of treating asthma in pregnancy far outweigh any potential risks from the patient’s usual medications.¹

GINA states that pregnant women and those planning a pregnancy should be asked whether they have asthma so that appropriate advice and medication can be given from the outset. If an objective confirmation of diagnosis is required, it is not advisable to carry out bronchial provocation testing or to step down controller treatment until after delivery. It might therefore be beneficial to use other types of diagnostic test to rule asthma in or out during pregnancy.¹ We will look in more detail at what those options are.

Which medications have been considered?

GINA has taken into account the most common asthma treatment and notes that inhaled corticosteroids (ICS) and beta₂-agonists are not associated with increased incidence of foetal abnormality. Importantly, ICS reduce the chance of exacerbations and stopping their use would be a significant risk factor. Indeed, one study reported that uncontrolled asthma in expectant mothers increased the risk of early-onset asthma in the child.² Another study found that treatment based on monthly FeNO (fractional exhaled nitric oxide, the most convenient biomarker of airway inflammation) with Asthma Control Questionnaire (ACQ) monitoring led to significantly fewer exacerbations and better foetal outcomes than an algorithm based on ACQ alone.³

What’s the advice?

The advice from GINA is to inform pregnant women that poorly controlled asthma and exacerbations are a much greater risk to the baby than their normal asthma treatments. It is recommended that monthly monitoring of asthma takes place during pregnancy, which could be achieved through pharmacist-clinician collaboration. Usual controller medications should also be continued throughout labour and delivery, with reliever use if necessary. Although acute exacerbations are rare at this point, bronchoconstriction can be induced by hyperventilation during delivery and should be managed with short-acting beta-agonists (SABA).¹

There is much less evidence for women with severe asthma who have been prescribed biologics. However, the advice is broadly the same, and women should be informed that the potential risks of exposure to the medication need to be balanced against the dangers of uncontrolled asthma.¹

Which additional management options are suitable?

Healthcare teams could look at additional asthma management tools, such as FeNO monitoring, during pregnancy. High FeNO levels are associated with an increased risk of asthma exacerbation and FeNO testing is a mild intervention, requiring only gentle effort by the patient, so it should prove very useful as an asthma risk estimator at this time.⁴

The benefits of FeNO-guided asthma management include a reduction in the rate of exacerbations by up to 50%, achieved through optimised therapy and uncovering non-adherence.⁵ Seeing their FeNO level can help patients visualise what is happening in their lungs that causes their discomfort, encouraging them to take their treatment as prescribed. FeNO testing is also non-invasive and gives clinicians results right at the point-of-care.

How does FeNO-guided management work in practice?

It has been suggested that asthma is the most common chronic medical disorder to complicate pregnancy, and that both mothers and healthcare professionals expect asthma to be controlled with minimum drug exposure to the developing foetus. Researchers also point out that, as well as the health risks and potential for low birthweight, asthma exacerbations in pregnancy cause maternal distress and increase the use of healthcare facilities.³

To investigate how to minimise drug use while still reducing the risk of exacerbations, researchers tested the idea that a management algorithm for asthma in pregnancy based on FeNO and symptoms could help. Groups of pregnant women were randomly assigned to treatment adjustment at monthly visits using clinical symptoms (control group) and FeNO levels (active intervention group). In the FeNO-controlled group, ICS dosage was stepped up when FeNO was over 29 ppb and stepped down when FeNO was under 16 ppb. The primary outcome was the total number of moderate and severe exacerbations, with analysis by intention to treat.

The findings were clearly in favour of using FeNO to guide asthma management in pregnancy. The exacerbation rate was significantly lower in the intervention group compared to control, at 0.288 vs 0.615 exacerbations per pregnancy: a 50% difference (p=0.001). The number need to treat was six, meaning only six patients needed to be managed with FeNO to avoid one exacerbation, which is a very encouraging number.