In every pregnancy, a woman starts out with a 3-5% chance of having a baby with a birth defect. This is called her background risk. This sheet talks about whether asthma may increase the risk for birth defects over that background risk. This information should not take the place of medical care and advice from your health care provider.

What is asthma?

Asthma refers to inflammation (swelling and tightening) in the airways of the lungs. When an asthma attack happens, it is difficult for air to pass through the lungs which leads to wheezing, coughing, and trouble breathing. Asthma is often treated with a combination of short acting inhalers for immediate symptom relief and daily medicines to reduce inflammation.

Triggers that can cause an asthma attack vary from person to person. Common triggers include breathing in cold air, cold/flu viruses, strenuous exercise, chemicals, cigarette smoke, and allergies to dust, animals, pollen, or mold. Avoiding these triggers can reduce the number of asthma attacks.

I have asthma and I am planning on getting pregnant. Is there anything I need to know?

Asthma management during pregnancy should continue to include the medicines that best control your asthma symptoms.

It is not possible to predict how a woman’s asthma will act during pregnancy. For about one third of women, symptoms will improve during pregnancy, another one third will have no change in asthma symptoms, and a final one third of women will have symptoms that become worse. It appears that the more severe the asthma is when you conceive, the more likely it is that the symptoms will get worse during pregnancy. Therefore, it is important that a woman’s asthma be in good control with carefully chosen medications prior to getting pregnant.

Can asthma cause birth defects?

Some studies have suggested an increased chance for birth defects while others have not. In these studies, it is difficult to determine whether the problems noted were due to the mother’s asthma, the medications needed to control the asthma, or from other factors. If a pregnant woman has trouble breathing she will take in less oxygen. This could lead to a lower amount of oxygen getting to the baby. Low oxygen to the developing baby could cause problems in organ development. If there is a risk from asthma itself, it is expected to be very low. The vast majority of women with asthma have babies without birth defects.

Can asthma lead to any other pregnancy problems?

Yes. Maternal asthma, especially poorly controlled asthma, is associated with higher rates of pregnancy complications, such as placental problems, high blood pressure, premature delivery, higher rates of cesarean section, and low birth weight. It is important for women who are pregnant to speak with their health care provider about the best way to treat their asthma during pregnancy. The benefits of treating asthma during pregnancy generally outweigh the potential risks of the medication. In fact, women with well-controlled asthma are not expected to have a greater chance for pregnancy complications than women without asthma.

Can taking medication for asthma during pregnancy cause birth defects or other pregnancy complications?

Most asthma medications have not been shown to have harmful effects on the developing baby. Speak with your healthcare provider and contact MotherToBaby with questions about your specific medications.

For more information about asthma medicines during pregnancy, see the MotherToBaby fact sheets at Some of the MotherToBaby sheets on medications that might be used for asthma are also listed here: prednisone/prednisolone (, albuterol (, salmeterol (, formoterol ( and inhaled corticosteroids (

If I have asthma, can I breastfeed my baby?

Most asthma medications are compatible with breastfeeding. For example, the amount of medication in breastmilk from fast acting inhalers and inhaled corticosteroids is expected to be too small to be harmful for an infant. For more information about asthma medicine during breastfeeding, contact MotherToBaby with your specific medication(s). Be sure to talk to your health care provider about all or your breastfeeding questions

What if the father of the baby has asthma?

A father’s asthma or a father’s use of asthma medicines does not increase the chance for birth defects or pregnancy complications. In general, exposures that fathers have are unlikely to increase risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures and Pregnancy at

MotherToBaby is currently conducting a study looking at asthma and the medication used to treat asthma in pregnancy. If you are interested in taking part in this study, please call 1-877-311-8972 or sign up at

Selected References:

  • Ali Z. 2017. Asthma and Pregnancy: Possible to prevent complications?- With Special reference to the impact of obesity and type of airway inflammation. Dan Med J. 64(12).
  • Blais L, et al. 2010. Effect of maternal asthma on the risk of specific congenital malformations: A population-based cohort study. Birth Defects Res A 88(4):216-222.
  • Garne E, et al. 2015. Use of asthma medication during pregnancy and risk of specific congenital anomalies: A European case-malformed control study. J Allergy Clin Immunol. Jul 25. pii: S0091-6749(15)00837-4.
  • Kallen B 2007. The safety of asthma medications during pregnancy. Expert Opin Drug Saf 6(1):15-26.
  • Kwon HL, et al. 2006. The epidemiology of asthma during pregnancy: prevalence, diagnosis, and symptoms. Immunol Allergy Clin North Am 26(1):29-62.
  • Mehta N, et al. 2015. Respiratory disease in pregnancy. Best Pract Res Clin Obstet Gynaecol. 29(5):598-611.
  • Murphy VE, et al. 2005. Asthma during pregnancy:mechanisms and treatment implications. Eur Respir 25:731-750.
  • Namazy JA, Schatz M. 2015. Pharmacotherapy options to treat asthma during pregnancy. Expert Opin Pharmacother;16(12):1783-91.
  • National Asthma Education and Prevention Program. Working Group. 2004. Report on managing asthma during pregnancy: Recommendations for pharmacologic treatment. Update 2004. NIH publication NO.05-5236. Bethesda, MD: US Department of Health and Human Services; National Institutes of Health; National Heart, Lung and Blood Institute.
  • Schatz M, Dombrowski MP 2009. Clinical practice: Asthma in pregnancy. N Engl J Med 360(18):1862-1869.