Asthma in pregnancy

Photo of a pregnant woman (PantherMedia / Alena Brozova)

Many pregnant women who have asthma worry that their medication might harm their child. But most asthma medications are considered to be safe in pregnancy too. Untreated asthma can have serious consequences.

It is estimated that about 1 out of 5 pregnant women with asthma need treatment for asthma attacks. But good asthma control, particularly with the regular use of inhaled corticosteroids, can prevent these attacks. And there are a number of things you can do to avoid possible triggers of asthma attacks.

In many women who have asthma, being pregnant doesn’t affect their symptoms. Their asthma sometimes even get better at first. But the physical changes that happen during pregnancy make asthma worse in 1 out of 3 women. Towards the end of pregnancy it often becomes increasingly difficult to stay physically active. Carrying the extra weight around can even make women who don’t have asthma feel out of breath. Many can’t sleep properly, and feel tired and exhausted.

How does asthma affect unborn children?

Mild or well-controlled asthma normally doesn’t cause any major health problems in either the woman or her baby. But asthma that isn’t well-controlled can have serious consequences for the woman and, more often, her baby. The unborn child needs a reliable supply of oxygen. If the mother has trouble getting enough oxygen herself during an asthma attack, her child might not get enough oxygen either. Although babies don’t breathe when they are inside the womb (uterus), they do need to get a steady supply of oxygen from their mother's blood to stay healthy and develop well.

If a pregnant woman who has moderate or severe asthma doesn’t control her asthma with preventive medications, she is at increased risk of having severe asthma attacks. This risk is higher in pregnancy because the hormonal changes and extra physical exertion make it more difficult to cope with more severe asthma attacks. Poorly controlled asthma increases the risk of:

  • Preterm birth: Where the baby is born too early and is then often underdeveloped.
  • Pre-eclampsia: This condition can develop during pregnancy, and is sometimes life-threatening for both the mother and child. Pre-eclampsia is associated with a sudden increase in blood pressure, and higher amounts of proteins in the mother’s urine (proteinuria). It also increases the risk of having seizures (convulsions).
  • Reduced growth and low birth weight: A lack of oxygen can affect the development of the child, who might then be born too small for his or her age, even after the full nine months of pregnancy.

Is medication for the control of asthma safe in pregnancy?

The negative consequences of leaving asthma untreated are worse than the possible side effects of asthma medication. So pregnant women who have asthma can usually carry on using the same medication as they did before they were pregnant. Although most asthma medications haven’t been specifically tested to see whether they are safe for use in pregnancy, there are no major safety concerns. The best-studied type of medication is inhaled corticosteroids (steroids). There are also no concerns about the use of long-acting beta2-agonists. However, these drugs should only be used in combination with a corticosteroid drug. This is because long-acting beta2-agonists can lead to severe asthma attacks if used on their own.

The use of inhaled corticosteroids is considered to be suitable and safe in pregnancy and while breastfeeding. But taking corticosteroid tablets regularly might have negative effects on the baby in the first three months of pregnancy. Compared to tablets, inhaled corticosteroids have less of an effect on the body as a whole. When inhaled, the drug goes straight to the lungs – only small amounts enter the rest of the body and reach the child. Similarly, only small amounts of the drug get into the mother’s breast milk.

The doctor will always try to find the lowest possible dose needed to keep the asthma under good control. It is also important to be informed about your own illness. Learning to manage asthma yourself (self-management) helps to keep asthma under control. As well as managing their asthma, it's important for pregnant women with this condition to have regular check-ups to monitor their health and their child’s health.

How safe is allergen-specific immunotherapy?

Many women who have allergies and would like to have children try out allergen-specific immunotherapy (desensitization). This treatment aims to help people react less sensitively to substances that trigger allergies (allergens). Immunotherapy usually takes three years or longer to complete.

Some women might consider starting this kind of treatment during pregnancy. This is not recommended, though, because too little is known about the benefits and dangers of immunotherapy in pregnancy. There is also a small risk of serious side effects that could even become life-threatening. Women who started allergen-specific immunotherapy before becoming pregnant are usually only advised to continue the therapy if it is well tolerated. But the dose should not be increased during pregnancy.

What else can you do to prevent asthma attacks?

Possible ways to prevent asthma attacks and lower the risk of the baby being born too small include:

  • Avoiding places where people smoke, because cigarette smoke can increase the risk of having an asthma attack. If a woman who has asthma still smokes herself, a (planned) pregnancy is a good reason to stop smoking – to gain better control over the asthma and protect the unborn child. The toxic substances in tobacco can have various harmful effects, including restricting the baby’s growth and causing health problems after birth.
  • Avoiding other things that trigger asthma attacks whenever possible. Depending on the type of allergy, triggers might include animal fur, pollen, cold air or dust mites.
  • Preventing heartburn. Heartburn is caused by stomach acid flowing back (reflux) into the food pipe, and is a common problem in pregnancy. Severe heartburn can trigger asthma attacks. Many women try to prevent or reduce heartburn by keeping their head higher than the rest of their body when they lie down. It can also help to eat several small meals a day so that your stomach doesn’t become too full.

How can asthma or allergies be prevented in the baby?

If both the mother and father stop smoking, they can reduce the chances of their child developing asthma. But there is no special "pregnancy diet" that has been shown to protect babies from asthma or allergies. In other words: Although it is important for pregnant women to avoid foods that can trigger asthma attacks, there is no reason for them to change their diet in order to protect their child from developing allergies later on.

It is generally important to pay attention to your own health during pregnancy. In women who have asthma, this also means making sure your asthma is well-controlled. But there’s no point in constantly worrying about asthma triggers, the foods you eat and other things. If asthma is well-controlled, there is every reason to believe that the pregnancy will go well for both the mother and child.