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Keeping asthma under control during pregnancy is important for mom and baby.1 About 6% to 8% of pregnant women in the United States have asthma.1,2 With the right treatment, most women can keep their asthma under control and have a healthy baby.

What are the risks of asthma during pregnancy?
A developing baby needs a constant supply of oxygen for normal growth. The key is to manage your asthma symptoms, so that you and your baby get enough oxygen.

Risks of poorly controlled asthma are:3

  • High blood pressure (preeclampsia)
  • Slower growth and low birth weight
  • Birth before 37 weeks (preterm birth)

Are asthma medications safe to take during pregnancy?
It is safer for pregnant women to take asthma medications than to have asthma symptoms and flare ups.1 More than 60% of women with asthma take medications during their pregnancy.2

The National Heart, Lung, and Blood Institute recommends short-acting beta-agonists and inhaled corticosteroids.1 These medications are used often to treat pregnant women.2,4 They do a good job controlling asthma symptoms. The information about their safety during pregnancy is reassuring.1 Your health care provider will recommend the safest medication and dosage for you.

If you are getting allergy shots when you become pregnant, you may be able to continue.3 Starting allergy shots while pregnant is not recommended.

How can I learn more about medication safety during pregnancy?
Your health care provider is the best person to ask before starting or stopping a medication during pregnancy. You can find additional information about a medication on its drug label.

A five-letter system has been used to classify medications and their safety during pregnancy. Medications are designated as Category A, B, C, D, or X. The category depends on the types of studies that have been done and the outcomes. For Category A drugs, high quality studies in humans have shown no risks to the baby. For Category X, there is evidence of risk to the baby, and these risks clearly outweigh the benefits of taking the medication.5

The US Food and Drug Administration thinks that the Category system oversimplifies the information about how safe a medication is.6 This classification system will be phased out, starting in June 2015. The label on prescription medications will have new sections. These sections will provide more details about the safety of the medication.

  • Pregnancy: This section will summarize the risks of taking this medication while pregnant. It will include information about labor and delivery.
  • Breastfeeding: This section will tell you how much of the medication passes into breast milk. It will explain how the medication might affect a baby.
  • Females and Males of Reproductive Potential: This section will explain whether pregnancy testing or birth control are needed while taking the medication. It will say if the drug could make it harder to get pregnant.

The new label will also include information about “pregnancy exposure registries”, if any are available.6 These registries collect information about women who take certain medications while they are pregnant.

Does asthma get better or worse during pregnancy?
For about one-third of women, asthma improves during pregnancy. For another one-third, it gets worse.1 One study showed that asthma severity can change throughout the pregnancy.4 For example, you may need less medication during the first trimester, but more during the second, and less again during the third.

The National Heart, Lung, and Blood Institute recommends monitoring your lung function at every prenatal visit.1 This way, you and your provider will know whether you need more or less medication.

How common are asthma attacks during pregnancy?
Asthma attacks happen in 3% to 6% of pregnancies with asthma.4 They are most likely to happen during the second and third trimesters. The highest risk is at six months.

It is important that you are able to recognize the signs of an asthma attack early.3 Signs include coughing, chest tightness, shortness of breath, and wheezing. Using your peak flow meter, you may find that your peak expiratory flow has decreased by 20%. It could be a sign of an asthma attack if the baby seems to be moving less.

Ask your health care provider to give you a written Asthma Action Plan. Your plan should tell you how to start treatment at home.3 Early treatment reduces the risk of low oxygen flow to the baby. If you continue to have symptoms after at-home treatment, seek medical attention. You should also consult your health care provider if you think the baby may be moving less than normal.

What can I do to prevent asthma attacks?
Avoiding asthma triggers can improve your health and reduce the amount of medication that you need.3

Tobacco smoke is a trigger, and it is important for anyone with asthma to avoid it. It is especially important to avoid tobacco smoke when you are pregnant. If you smoke while you are pregnant, your baby is more likely to have asthma. Children whose mom smoked during pregnancy have a higher risk of wheezing and asthma at age five.1 Children exposed to smoke prenatally have life-long decreases in lung function.1

Do not let anyone smoke around you, either. Not only can second-hand smoke trigger an asthma attack, but it is bad for the baby as well.3 Recently, a study showed that prenatal second-hand smoke increased the risk of childhood asthma.7

Will my asthma get worse during labor and delivery?
Asthma does not usually flare up during labor and delivery.3 You can continue taking your asthma medications during labor and delivery. Your health care provider may want to check your lung function while you are in labor.

Can I breastfeed if I am taking asthma medications?
Yes, you can breastfeed if you are taking asthma medications.3 The American Academy of Pediatrics recommends breastfeeding for one year or more.8 Breastfeeding may protect your child against asthma and other allergic diseases. If children with a family history of allergic disease are fed only breast milk for the first three to four months, their risk of allergic disease is 42% lower.8

Written by: Sarah O'Brien | Last Reviewed: May 2016.
  1. National Heart, Lung, and Blood Institute. Expert panel report 3 (EPR-3): Guidelines for the diagnosis and management of asthma - Full Report 2007. Accessed 11/12/14 at:
  2. Hansen C, Joski P, Freiman H, et al. Medication exposure in pregnancy risk evaluation program: the prevalence of asthma medication use during pregnancy. Matern Child Health J. 2013;17:1611-1621.
  3. National Heart, Lung, and Blood Institute. Working group report on managing asthma during pregnancy: Recommendations for pharmacologic treatment. Update 2004. Accessed 1/20/15 at:
  4. Charlton RA, Hutchison A, Davis KJ, de Vries CS. Asthma management in pregnancy. PLoS One. 2013;8:e60247.
  5. Black RA, Hill DA. Over-the-counter medications in pregnancy. Am Fam Physician. 2003;67:2517-2524.
  6. Food and Drug Administration. Pregnancy and lactation labeling final rule. Accessed 1/20/15 at:
  7. Simons E, To T, Moineddin R, Stieb D, Dell SD. Maternal second-hand smoke exposure in pregnancy is associated with childhood asthma development. J Allergy Clin Immunol Pract. 2014;2:201-207.
  8. Section on Breastfeeding. Breastfeeding and the use of human milk. Pediatrics. 2012;129:e827-e841.