Important Safety Information | NIOX VERO® User Manual (PDF)

For UK Healthcare Professionals Only


Controlling asthma in pregnancy

Symptoms worsen for around a third of pregnant women with asthma yet many are reluctant to take medication, which they believe could affect the baby. It’s a tricky balance – mental health and peace of mind are of paramount importance, but uncontrolled asthma also brings risks. This article looks at the evidence and at the latest advice on managing asthma in pregnancy.

Listen to this article:

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 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.

Our latest webinar:

What’s more, the women in the FeNO group experienced significantly better quality of life (p=0.037), including improved mental health, with the mean ICS dosage lower in the FeNO group throughout the study, easing another concern. Neonatal hospitalisations were also significantly reduced by 44%.

In keeping with GINA’s recommendation that pregnant women maintain controller use of ICS, 26% more women received ICS as a result of FeNO assessment compared to those managed only with clinical assessment.

FeNO testing takes less than two minutes to perform and see the results at the point-of-care. The process is safe, easy and non-invasive with a handheld device such as NIOX VERO®, in patients from the age of four generally and seven in the US.

It is good to know that there are tools that can help to manage asthma without significant effort by the patient or destabilising crucial controller treatment plans. Incorporating simple measures like FeNO testing into the management algorithm can help to reduce asthma exacerbations by up to 50%. Requiring only one gentle exhalation to achieve a successful test and reliable result, the gold standard FeNO device, NIOX VERO®, really makes testing safe and easy for all.

Share this article:

Discover NIOX® today

Learn more about the gold standard FeNO device.

Related Articles:

How can FeNO improve asthma management and relieve the pressure on the healthcare system?

Understanding Type 2 inflammatory pathways

A review of national and international guidelines for FeNO testing


1. Global Initiative for Asthma (GINA) 2022. Chapter 3: Managing asthma with multimorbidity and in specific populations, p. 100-101.
2. Liu X, Agerbo E, Schlunssen V, et al. Maternal asthma severity and control during pregnancy and risk of offspring asthma. J Allergy Clin Immunol 2018; 141: 886-892 e883.
3. Powell H, Murphy VE, Taylor DR, et al. Management of asthma in pregnancy guided by measurement of fractional exhaled nitric oxide: a double-blind, randomised controlled trial. Lancet 2011; 378: 983-990.
4. Busse WW et al. Baseline FeNO as a prognostic biomarker for subsequent severe asthma exacerbations in patients with uncontrolled, moderate-to-severe asthma receiving placebo in the LIBERTY ASTHMA QUEST study: a post-hoc analysis. Lancet Respir Med. 2021;9(10):1165-1173.
5. Petsky HL et al. Tailoring asthma treatment on eosinophilic markers (exhaled nitric oxide or sputum eosinophils): a systematic review and meta-analysis. Thorax. 2018;73(12):1110-1119.