Pregnancy and Asthma

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Summary of practice points

 Level of evidence
Poorly controlled asthma increases the risk of pre-eclampsia, prematurity, low birth weight and perinatal mortality (III). Good asthma control reduces these risks (IV).

III & IV
The pharmacological treatment of asthma during pregnancy should be the same as for non-pregnant women. IV
Most medications for asthma have good safety profiles in pregnant women. III
If oral corticosteroids are clinically indicated for an exacerbation they should not be withheld because a woman is pregnant. IV
ICS should not be changed in pregnant women whose asthma is well controlled. However, women who are planning a pregnancy and already using ICS should switch to budesonide, a Category A drug. IV
Salmeterol and eformoterol should not be stopped if a pregnant woman is already using them, but if possible, they should be avoided during the first trimester. [√]
Remind parents that passive smoking increases the risk of childhood asthma and other respiratory conditions in their child. Avoidance of environmental tobacco smoke may reduce the risk of childhood asthma. III-2

Maintaining good asthma control during pregnancy is important for the health of both the mother and baby. Appropriate and ongoing asthma care can successfully manage deteriorations and exacerbations of asthma in most cases. At all times during pregnancy, the use of any medicine is a balance between the justification for its use in maintaining asthma control and the potential for adverse effects.

Breathlessness during pregnancy is common and is usually due to hormonal changes, not asthma. Spirometry can assist in determining the cause. The use of bronchial provocation tests for the diagnosis of asthma in pregnant or lactating women should only be performed on the advice of a respiratory specialist.

Before pregnancy

Women with asthma who are planning to become pregnant should stop smoking.

Women should be advised that, if they become pregnant:

  • their asthma and pregnancy may interact
  • good asthma control is important
  • their asthma should be reviewed regularly
  • many asthma medications, including most inhaled corticosteroids (ICS), have a good safety profile and should be continued during pregnancy.

Because of the risk of precipitating an exacerbation, asthma medications should not be changed in women whose asthma is well controlled and who present after they have become pregnant. However, in women who are planning a pregnancy and are already using ICS, budesonide is recommended, because it is rated Category A by the Australian Drug Evaluation Committee (ADEC). More data on use in pregnant women are available for budesonide than for other ICS.1 However, there are no data indicating that other ICS are unsafe during pregnancy.

Review asthma control after any change in the medication regimen.

Practice tips

Women with asthma who are planning to become pregnant should be advised to stop smoking.

Women should be advised that, if they become pregnant:

  • their asthma and pregnancy may interact
  • good asthma control is important
  • their asthma should be reviewed regularly
  • many asthma medications, including most ICS, have a good safety profile and should be continued during pregnancy.

Antenatal care

Exacerbations of asthma requiring medical intervention occur in about 20% of pregnant women and about 6% will require hospitalisation.2 Regular evaluation and monitoring of asthma control is, therefore, recommended throughout pregnancy.1,3 Poorly controlled asthma increases the risk of pre-eclampsia, preterm birth, low birth weight and perinatal mortality. Good asthma control can reduce these risks.1

The goals of management during pregnancy are to maintain asthma control so as to ensure the oxygen supply required for normal foetal development, as well as to maintain maternal health and quality of life. The pharmacological treatment of asthma during pregnancy should be the same as for non-pregnant women. (See Medications during pregnancy and lactation)

  • Doses of ICS should be the minimum necessary to control symptoms and maintain normal or best lung function.
  • Peak expiratory flow monitoring and regular review of asthma every 4-6 weeks is recommended.3 This can provide reassurance for the pregnant woman and her healthcare providers. Close cooperation between all health professionals caring for the pregnant patient is important to ensure the best asthma management.
  • Acute asthma exacerbations may reduce the amount of oxygen available to the foetus. Any deterioration in symptoms should be managed promptly.
  • Trigger factors should be avoided or minimised where possible. Minimise exposure to known allergens and irritants.
Practice points
  • Poorly controlled asthma increases the risk of pre-eclampsia, prematurity, low birth weight and perinatal mortality. (III) Good asthma control reduces these risks. (IV)
  • The pharmacological treatment of asthma during pregnancy should be the same as in non-pregnant women. (IV)
  • Women who are planning a pregnancy and already using ICS should switch to budesonide, a Category A drug. (IV)

Asthma exacerbations during pregnancy

Asthma exacerbations during pregnancy may be related to poor pregnancy outcomes.2  Exacerbations during pregnancy:

  • occur primarily between 17 and 36 weeks gestation
  • are often triggered by viral infection and non-adherence to ICS medication
  • significantly increase the risk of having a low-birth-weight baby.2

The effective management and prevention of asthma exacerbations during pregnancy is important for the health of both mother and baby.2

  • ICS use may reduce the risk of exacerbations during pregnancy.
  • Prescribe oral corticosteroids in pregnant women when clinically indicated.

Practice tips

Asthma exacerbations during pregnancy should be managed:

  • promptly
  • in the same way as an exacerbation at any other time
  • with oral corticosteroids if clinically indicated.

If antibiotics are to be used their safety in pregnancy should be confirmed (refer to ADEC. Prescribing medicines in pregnancy. 4th edition, 1999).

Delivery

Except in the most severe cases, asthma should not preclude a vaginal delivery. Caesarean section should be no more common than in women without asthma. Exacerbations of asthma are uncommon during labour and delivery.3

Post-partum phase

Review asthma regularly after delivery.

Remind parents that passive smoking increases the risk of childhood asthma and other respiratory conditions in their child. The link between exposure to environmental tobacco smoke in early childhood and increased risk of respiratory illnesses, including asthma, has been well documented in epidemiological studies.4 Avoidance of environmental tobacco smoke may reduce the risk of childhood asthma. (III-2)

Breastfeeding should be encouraged as it may reduce the risk of childhood asthma, especially in children with a family history of atopy.5 For more information on breastfeeding and asthma, see Prevention of Asthma.

Practice tips

  • Advise pregnant women to avoid passive smoking
  • Encourage breastfeeding

Medications during pregnancy and lactation

It is safer for pregnant women to maintain control of their asthma with appropriate medications than for them to have asthma symptoms and exacerbations.1

  • The pharmacological treatment of asthma during pregnancy should be the same as in the non-pregnant state. If oral corticosteroids are clinically indicated for an exacerbation they should not be withheld because a woman is pregnant.1
  • If maintenance treatment with ICS was necessary before the pregnancy, it should be continued during pregnancy.1 As in the non-pregnant state, the dose should be the minimum necessary to control symptoms and maintain normal or best lung function.
  • Most medications for asthma have good safety profiles in pregnancy. There is some evidence that the use of oral corticosteroids (particularly in the first trimester) is associated with a slight increase in the incidence of cleft lip with or without cleft palate. This finding is based on small numbers and from studies not specifically designed to assess the risk.
  • There are limited data describing the effectiveness and/or safety of using combination therapy during pregnancy.1 To date, there are no studies examining the effects of long-acting beta2 agonists on pregnancy outcomes.6 Salmeterol and eformoterol are rated Category B3 drugs. These medicines should not be withdrawn in women who present after they have become pregnant if they are controlling symptoms. It is recommended that these agents be avoided, if possible, during the first trimester. No safety studies of leukotriene receptor antagonists in pregnancy have been published. They should only be used where other medications have not achieved satisfactory asthma control.
  • Asthma medications can enter breast milk, but their concentrations are generally so small that they appear to have no adverse effects on the baby.3

For further information about drugs for use during pregnancy and lactation, see the Prescribing medicines in pregnancy database.

Practice points
  • Most medications for asthma have good safety profiles in pregnant women. (III)
  • If oral corticosteroids are clinically indicated for an exacerbation they should not be withheld because a woman is pregnant. (IV)
  • The ICS regimen should not be changed in pregnant women whose asthma is well controlled. However, women who are planning a pregnancy and already using inhaled corticosteroids should switch to budesonide, a Category A drug. (IV)
  • Salmeterol and eformoterol should not be stopped if a pregnant woman is already using them, but if possible, they should be avoided during the first trimester. [√] 

Smoking

Women should stop smoking before becoming pregnant and avoid environmental tobacco smoke during pregnancy. Parents should ensure their children are not exposed to tobacco smoke.

  • Smoking during pregnancy increases the risk of premature labour, low birth weight and respiratory disorders during early infancy.
  • Children exposed to tobacco smoke during gestation or infancy are more likely to develop asthma.
Practice point

Remind parents that passive smoking increases the risk of childhood asthma and other respiratory conditions in their child. Avoidance of environmental tobacco smoke may reduce the risk of childhood asthma. (III-2)

More information