Asthma is a potentially serious lung condition that affects between 4 and 8 percent of pregnant women (1, 2). It is one of the most common health conditions that can complicate pregnancy.
Pregnant women with asthma generally do not have an increased risk of pregnancy complications as long as their asthma is well controlled. However, poorly controlled asthma can pose a number of health risks to mother and baby. Pregnant women with asthma should have regular medical care to keep their asthma under control to protect their health and their baby’s health.
What are the symptoms of asthma?
Symptoms of asthma include:
- Wheezing (a whistling sound when the person breathes)
- Chest tightness
- Persistent cough (especially at night or early morning)
- Shortness of breath
These symptoms occur when the airways become partially blocked due to swelling (inflammation) of the airway walls, accumulation of mucus, and spasm of muscles surrounding the airways. Symptoms of asthma often can be prevented or controlled with proper treatment.
How is asthma diagnosed?
A health care provider diagnoses asthma based on physical symptoms and a test called spirometry. To take the test, an individual takes a deep breath and then blows hard into a device called a spirometer. The spirometer measures the largest amount of air the person can exhale (blow) after a deep breath.
Some pregnant women who do not have asthma may experience shortness of breath due to normal hormonal changes of pregnancy and the growing uterus crowding the lungs. Spirometry can rule out asthma in these women.
What pregnancy risks are associated with poorly controlled asthma?
Poorly controlled asthma can deprive the baby of oxygen, increasing the risk of premature birth (before 37 completed weeks of pregnancy), poor fetal growth and low birthweight (less than 5½ pounds) (1, 2, 3). Babies who are born too small and too soon are at increased risk of newborn health problems, such as breathing difficulties, and lasting disabilities, such as mental retardation and cerebral palsy. Women with poorly controlled asthma also are more likely to develop preeclampsia, a pregnancy-related form of high blood pressure that can result in poor fetal growth and other pregnancy complications (1, 2, 3).
How is asthma treated during pregnancy?
The health care provider recommends an individualized treatment plan that includes helping the woman identify and avoid substances that trigger her symptoms. The provider most likely prescribes medicine to help prevent or control the women’s symptoms.
What are some common asthma triggers?
About 70 percent of individuals with asthma have allergies (4). Common allergens (substances that cause allergy symptoms), such as pollens, molds, animal dander (dead skin flakes), dust mites and cockroaches, can trigger asthma symptoms. Individuals can help reduce their exposure to these allergens by (2, 3, 4, 5):
- Closing home and car windows and using air conditioning during the outdoor allergy season
- Avoiding outdoor activities when the pollen count is high
- Showering after spending time outdoors to get pollen off hair and skin
- Staying away from freshly mowed lawns
- Not raking leaves
- Wearing a mask when vacuuming (or using filtering vacuums)
- Keeping pets out of the bedroom at all times
- Covering pillows and mattresses in plastic covers to help avoid dust mites
- Washing bedding in hot water (130°F) once a week to help kill dust mites
- Using window shades instead of blinds and removing blinds and carpet that collect dust
- Keeping humidity in the home below 60 percent to control dust mites
If these measures don’t provide enough relief, the provider may recommend an allergy medicine. If a woman is already receiving allergy shots, she can safely continue them in pregnancy (1). However, a woman should not start allergy shots for the first time during pregnancy because of the slight risk of a serious allergic reaction called anaphylaxis (1).
Other asthma triggers include cold air, strong odors (such as paint or perfumes), infections, secondhand smoke, smoke from wood-burning stoves or fireplaces, high levels of air pollution, and exercise. If exercise triggers asthma symptoms, a woman should ask her provider if she should use her medicine before exercising. Pregnant women who limit their exposure to allergens and other asthma triggers may need to take less medicine to control their symptoms.
Are asthma medicines safe in pregnancy?
Most asthma medicines are safe in pregnancy. A pregnant woman should never stop her asthma medicine without the advice of her health care provider because persistent or worsening asthma symptoms can pose a risk to her and her baby.
The National Asthma Education and Prevention Program’s guidelines on asthma and pregnancy recommend a step-wise approach to managing asthma (6). The guidelines recommend certain medicines for pregnant women, with others added if symptoms become more severe:
- Mild, intermittent asthma (symptoms 2 days a week or less): A fast-acting, inhaled, bronchodilator spray (“rescue medication” which opens and relaxes airways) called albuterol (Ventolin, Proventil and others) is recommended to relieve occasional symptoms.
- Mild, persistent asthma (symptoms more than 2, but less than 7, days a week): Daily treatment with low doses of an inhaled steroid, such as budesonide (Advair and others), is recommended to help prevent symptoms.
- Moderate, persistent asthma (daily symptoms): Daily treatment with either low doses of an inhaled steroid plus a long-acting bronchodilator such as salmeterol, or daily treatment with a medium-dose inhaled steroid is recommended.
- Severe, persistent asthma (symptoms occur throughout the day): Daily treatment with high-doses of an inhaled steroid plus salmeterol, and in some cases, treatment with oral steroids (prednisone and others) are recommended.
In most cases, health care providers treat asthma with inhaled medications because very little of the drug reaches the fetus. But if a woman has severe asthma that cannot be controlled with inhaled medications, she may need to take an oral steroid, such as prednisone, until symptoms are under control. This drug may pose a slightly increased risk of premature birth, so it’s recommended only when needed (2, 6).
Does pregnancy affect asthma symptoms?
Most pregnant women with asthma experience a change in the severity of their symptoms, even when they take their medicine as directed. Studies suggest that symptoms worsen in about one-third of pregnant women (especially in the late second and early third trimesters), improve in one-third and remain unchanged in one-third (1, 3, 4).
Health care providers regularly monitor the lung function of a pregnant woman with asthma using spirometry, so that her asthma medications can be adjusted, if necessary. A woman also should tell her provider if her symptoms improve or worsen.
The reasons why asthma symptoms may change during pregnancy are not well understood. One factor that may contribute to worsening symptoms is gastroesophageal reflux (heartburn). A woman can help improve heartburn symptoms by sleeping with her head elevated, eating smaller and more frequent meals and not eating within 2 hours of bedtime. Her provider can recommend a safe antacid.
Pregnant women with asthma also should get a flu shot in October or November because the flu can trigger serious asthma episodes. (The flu shot is recommended for all pregnant women during the flu season.)
Do pregnant women with asthma need any special tests, other than spirometry?
Women with well-controlled, mild asthma may not need any special tests (unless they are recommended for other reasons). But providers often recommend repeated ultrasounds starting around 32 weeks of pregnancy for women with poorly controlled or moderate-to-severe asthma (1). Ultrasounds can show if the baby is growing at a normal rate.
The provider also may recommend fetal heart rate testing (such as the non-stress test) to check on fetal well-being. Abnormal results on these tests can alert the provider when special care may be needed.
Do labor and delivery trigger asthma symptoms?
Only about 10 percent of pregnant women with asthma develop symptoms during labor and delivery (5). Women with asthma should continue taking their usual medications during labor and delivery (1). If a woman develops asthma symptoms, they can be controlled with medication.
Are asthma medications safe during breastfeeding?
Asthma medications do enter a woman’s breastmilk, but the amounts are very low and are safe for the baby. Occasionally, a baby may become irritable or have trouble sleeping if the mother is taking high doses of certain asthma medications. These effects often can be prevented if the mother takes her asthma medication 3 or 4 hours before the next feeding. The baby’s provider and the woman’s provider can help her adjust her medication schedule, if necessary, so that mother and baby can obtain the health benefits from breastfeeding.
References
- American College of Obstetricians and Gynecologists (ACOG). Asthma in Pregnancy. ACOG Practice Bulletin, number 90, February 2008.
- Dombrowski, M.P. Asthma and Pregnancy. Obstetrics and Gynecology, volume 108, number 3, September 2006, pages 667-681.
- National Asthma Education and Prevention Program. Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma. National Heart, Lung and Blood Institute, 2007.
- American Academy of Allergy, Asthma and Immunology. Diseases 101: Asthma Statistics. Accessed 10/15/08.
- American College of Allergy, Asthma and Immunology. When Pregnancy Is Complicated by Allergies and Asthma. Accessed 10/10/08.
- National Asthma Education and Prevention Program. Managing Asthma During Pregnancy: Recommendations for Pharmacologic Treatment. National Heart, Lung, and Blood Institute, 2004.
January 2009
