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How to manage asthma during pregnancy

Rebecca Elder
Asthma Nurse Specialist
Asthma UK

The British Guideline on the Management of Asthma states that "pregnancy can affect the course of asthma and asthma can affect pregnancy outcomes".(1) The Asthma UK Adviceline receives many calls and emails from women with asthma who are unsure about what to expect from or how to react to the changes that they experience in their asthma as a result of their pregnancy. If asthma is well controlled throughout pregnancy there is little or no increased risk of adverse maternal or fetal complications.(1) Healthcare professionals have an important role to play in helping women with asthma to achieve and maintain this control. So how can they best achieve this?

The effect of asthma on pregnancy
Like pregnancy, asthma varies enormously from woman to woman. It is generally accepted, however, that during pregnancy there is a "rule of one-thirds": about one-third of women experience an improvement in their asthma, one-third experience a worsening of their symptoms, and one-third experience no change.(2)
Women with mild asthma are unlikely to experience problems, but those with severe asthma are at greatest risk of deteriorating asthma control, especially later in pregnancy.(3)
Asthma has no effect on pregnancy outcome for the majority of women if it is well controlled. Fetal hypoxia, as a result of asthma exacerbations, poses a greater threat to the wellbeing of the fetus than most medication side-effects.(3) Maternal complications from poorly controlled asthma include:

  • Hyperemesis.
  • High blood pressure.
  • Pre-eclampsia.
  • Vaginal haemorrhage.

Fetal complications of poorly controlled asthma include increased risk of:

  • Stillbirth.
  • Prematurity.
  • Neonatal hypoxaemia.
  • Low newborn assessment scores.
  • Increased perinatal mortality.

Effective asthma management during pregnancy
There is overwhelming evidence that asthma should be as well controlled as possible throughout pregnancy.(1) Ideally, preconceptual counselling about asthma management should be offered. A written personal asthma action plan is the most effective way to ensure that the client (as well as any other healthcare professional who becomes involved) understands the medications she is taking and the steps to take should her asthma get worse or improve.
In addition to general asthma management advice, there are some specific issues that may affect a client's asthma control during pregnancy, and these need to be addressed in order to protect her health and that of her baby.

Smoking not only harms the fetus directly but also exacerbates asthma symptoms. A recent study showed that, in people with asthma, lung function improved just one week after stopping smoking, highlighting the importance and benefit of smoking cessation.(4) Smoking during pregnancy increases the risk of the baby being wheezy or having breathing difficulties by 35%, and children whose parents smoke are 1.5 times more likely to develop asthma.(5.6) In addition, women who smoke during pregnancy are more likely to have a miscarriage, more likely to go into premature labour and more likely to have babies who are underweight.

Safety of medications and treatments
Although women will understandably be worried about the effects that any medications may have on their baby, the risk of harm to the fetus is minimal, but is greater if asthma is uncontrolled. It is particularly important to take a preventer inhaler on a daily basis to control the symptoms of asthma occurring and short courses of oral steroids if necessary. It is imperative that women with asthma understand that this is the case and feel reassured that they are doing the best thing for their health and the health of their baby. As discussed above, a written personal asthma action plan can help to achieve this.
The British Guideline on the Management of Asthma states that b(2)-agonists can be used as normal during pregnancy.(1) If a client needs to use her reliever more than once a day, it can be a sign that her asthma may not be well controlled and she should make an appointment for an asthma review. Breathlessness can also be caused by other factors, so it is important that the client has a thorough clinical assessment. Inhaled steroids are safe for the baby and can be used as normal. They have also been shown to decrease the risk of an acute attack of asthma in pregnancy and the risk of readmission following asthma exacerbation. Leukotriene antagonists should not be commenced during pregnancy, but may be continued in women who, before pregnancy, have demonstrated significant improvement in asthma control that was not achievable with other medications. Oral and intravenous theophyllines can also be used as normal during pregnancy, but measurement of theophylline levels is recommended for women requiring therapeutic levels to maintain asthma control. Protein binding decreases in pregnancy, resulting in increased free drug levels, and therefore a lower therapeutic range may be necessary.
The guideline also states that short courses of oral corticosteroids can be used in an exacerbation to regain optimum asthma control and thus reduce the risks to mother and fetus. There is no convincing evidence that short courses of steroids affect fetal growth or cause malformations. Chromones can also be used as normal during pregnancy.

A mother with asthma may also want to know whether there are steps she can take to prevent her child from developing asthma too, particularly with regard to diet during pregnancy. There is no convincing evidence that avoiding any foods during pregnancy will help prevent a baby from developing asthma. However, some research suggests that allergy to peanuts may develop in the womb. Current government advice is that if anyone in the immediate family has an allergic condition such as asthma, hay fever and eczema, the mother should avoid eating peanuts and food containing peanut products during pregnancy and while breastfeeding.

Effective asthma management during labour
It is unusual for asthma to cause problems in labour, as the body produces endogenous steroids. If a woman does get asthma symptoms during labour, she can use her reliever inhaler as normal.
Healthcare professionals can play an important role in reassuring their patient on these counts by drawing up a birth plan for them that takes their asthma into account and helps to reduce any fears they may have about giving birth. Women with asthma may safely use all forms of pain relief in labour. A regional blockade is preferable to a general anaesthetic if required.

Effective asthma management after pregnancy
Like all mothers, those with asthma should be encouraged to breastfeed. The WHO recommends mothers exclusively breastfeed their babies for the first six months and continue to the age of two (with complementary foods being introduced at six months).(7) Breastfeeding has been shown to reduce the risk of a baby developing atopic conditions.(8) Mothers with asthma should continue to take their asthma medications as normal. Medicines used to treat asthma are safe for nursing mothers as they do not affect the ability to produce breast milk.


If asthma is well controlled throughout pregnancy it should not pose a problem for clients. Healthcare professionals play a vital part in providing the information, advice and reassurance that pregnant women with asthma need. Collaboration is essential to ensure that all healthcare professionals give the consistent, clear message that using asthma medication is safer for mother and baby than the risks of uncontrolled asthma.



  1. British Thoracic Society, Scottish Intercollegiate Guidelines Network. British guideline on the management of asthma. Rev ed. Nov 2005. Available from:
  2. Juniper EF, Newhouse MT. Effect of pregnancy on asthma - a systematic review and meta-analysis. In: Schatz M, Zeiger RS, Claman HC, editors. Asthma and immunological diseases in pregnancy and early infancy. New York: Marcel Dekker; 1993.
  3. Schatz M, Harden K, Forsythe A, et al. The course of asthma during pregnancy, post partum, and with successive pregnancies: a prospective analysis. J Allergy Clin Immunol 1988;81:509-17.
  4. Chaudhuri R, Livingston E, McMahon AD, Lafferty J, Fraser I, Spears M, et al. Effects of smoking cessation on lung function and airway inflammation in smokers with asthma. Am J Respir Crit Care Med 2006;174:127-33.
  5. Jaakkola JJ, Gissler M. Maternal smoking in pregnancy, fetal development, and childhood asthma. Am J Public Health 2004;94:136-40.
  6. Department of Health. Report of the Scientific Committee on tobacco and health. London: HMSO; 1998.
  7. WHO Department of Nutrition for Health & Development, Department of Child and Adolescent Health & Development. The optimal duration of exclusive breastfeeding. Geneva: WHO; 2001.
  8. Saarinen UM, Kajosaari M. Breastfeeding as prophylaxis against atopic disease: prospective follow- up study until 17 years old. Lancet 1995;346:1065-9.

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British Guideline on the Management of Asthma