Asthma in Pregnancy

The instruction that matters most: do not stop your inhaler

The single strongest message in the UK guidance is about continuing treatment, not changing it. NICE guideline NG245, the joint BTS, NICE and SIGN asthma guideline, says at recommendation 1.12.1 that people with asthma "should have an asthma review during early pregnancy and in the postpartum period" and tells clinicians to "emphasise the importance and safety of maintaining good control of asthma during pregnancy and of continuing asthma medicines to avoid problems for themselves and their baby".

That wording is deliberate. The risk being managed is poorly controlled asthma, not the medicines used to control it. If you have quietly reduced or stopped a preventer inhaler since seeing a positive test, that is the thing to raise at your next appointment.

Which medicines carry on unchanged

NG245 is unusually specific about this, which makes it easy to check your own care against. Recommendation 1.12.3 says to advise using the following "as normal during pregnancy":

• short-acting and long-acting beta 2 agonists
• inhaled corticosteroids
• oral theophyllines

Recommendation 1.12.4 goes further on flare-ups: offer oral corticosteroids during pregnancy "if needed to treat exacerbations of asthma", and advise that the benefits of that treatment outweigh the risks. Recommendation 1.12.5 adds that leukotriene receptor antagonists and long-acting muscarinic receptor antagonists "should not be stopped during pregnancy" if they are needed for control. For breastfeeding, recommendation 1.12.6 says to use medicines as normal.

None of that means your dose is fixed. It means the decision to change one belongs with the clinician reviewing your control, not with a worried scroll through a leaflet at 2am.

How common is this, and whose number is it

The clearest published prevalence figure comes from the American body rather than the British one. ACOG Practice Bulletin No. 90, Asthma in Pregnancy, opens by describing asthma as a condition that "complicates approximately 4-8% of pregnancies". That is a US figure, drawn from US obstetric populations, and the full text of that bulletin sits behind an ACOG member login, so the abstract is the part of it any reader can verify. NICE does not publish an equivalent UK pregnancy prevalence figure in NG245, and we are not going to borrow the American one and label it British.

What your antenatal care looks like

Asthma alone does not usually move you onto a different pathway. It adds a review. The NHS page on asthma says simply that if you are pregnant you should tell your doctor or midwife about your asthma, because "it's important to manage asthma in pregnancy to keep you and your baby well". HSE Ireland gives the same framing on its asthma pages for people in Ireland.

In practice the review is looking at three things: how often you are reaching for a reliever, whether your inhaler technique has drifted, and whether anything in the pregnancy itself, such as reflux or a chest infection, is making control worse. NICE CKS on asthma sets out the same monitoring principles used outside pregnancy, and NG245 recommendation 1.11 asks clinicians to check adherence and inhaler technique at every asthma-related review.

When to treat it as urgent

An asthma attack in pregnancy is treated as an asthma attack, with the same urgency as at any other time. Breathlessness that is new, worse at rest, or not settling with your reliever is a reason to seek emergency help rather than wait for a routine appointment. Pregnancy causes its own breathlessness in the second and third trimesters, which is exactly why a change in your usual asthma pattern is worth flagging rather than filing under "normal pregnancy".

Labour and birth: one drug your team will avoid

This is where asthma genuinely changes something, and it is set out in NICE guideline NG121, which covers intrapartum care for women with existing medical conditions.

On pain relief, recommendation 1.4.1 says to offer women with asthma "the same options for pain relief during labour as women without asthma", and names Entonox (50% nitrous oxide plus 50% oxygen), epidural and combined spinal-epidural analgesia among them. There is no asthma-specific restriction on what you can have.

On drugs used around birth, recommendation 1.4.2 is a clear prohibition: do not offer prostaglandin F2 alpha, known as carboprost, to women with asthma, "because of the risk of bronchospasm". Carboprost is one of the drugs used for heavy bleeding after birth, so this is worth having written in your notes. Recommendation 1.4.3 says prostaglandin E1 and prostaglandin E2 can be considered for inducing labour in women with asthma, because there is no evidence that they worsen asthma. In other words, induction is not off the table; one specific haemorrhage drug is.

What to actually do next

Book an asthma review early rather than waiting for your first midwife appointment to raise it. Take your inhalers with you so technique can be checked. Ask for your asthma to be recorded in your maternity notes along with the carboprost point, because the people looking after you in labour may not be the people who reviewed your asthma in the first trimester. If you smoke, NG245 recommendation 1.12.2 asks your team to offer stop-smoking support, and that support is more effective in pregnancy than at almost any other point in life.

Finally, plan the postnatal review now. NG245 asks for one in the postpartum period, and it is the appointment most easily lost in the first weeks with a new baby.