Asthma in Pregnancy

The effects of your condition and its treatment

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If you have asthma and are pregnant or want to conceive, you may worry about how your asthma might impact your pregnancy and baby.

Between about 3% and 8% of pregnant women have pre-existing asthma. While some research shows asthma can cause pregnancy complications, it rarely poses a significant risk for a baby or mother when it is properly treated.

Understanding guidelines for using asthma medications during pregnancy, following doctors' recommendations for managing asthma, and knowing about any potential complications can help you plan a healthy pregnancy.

Doctor showing pregnant woman a peak flow meter
lostinbids / Getty Images

Symptoms of Asthma in Pregnancy

During pregnancy, you're likely to have the same asthma symptoms that you've had previously, including:

However, you may experience these to a greater or lesser extent than you did before conceiving. Approximately 30% of expectant women with asthma have more severe symptoms during pregnancy. Other women feel the same or notice their symptoms become milder.

When asthma does worsen, symptoms typically become most serious between 29 and 36 weeks gestation. Symptoms usually become less severe in weeks 36 to 40.

Don't assume that any breathing changes you are experiencing are a result of weight gain or pressure from your baby. Wheezing, for instance, is never a pregnancy-related symptom.

Risks and Complications

Most problems involving asthma during pregnancy are due to inadequate asthma treatment. These can affect both you and your baby.

Keeping your asthma symptoms properly treated and talking to your doctor about any changes in your symptoms can keep your asthma well-controlled and help prevent complications.

Your Health

Poorly controlled asthma during pregnancy can lead to:

Preeclampsia can result in various concerns, including pre-term birth and placental abruption. It should be monitored for and managed carefully.

Even if your asthma gets worse during pregnancy, it doesn't appear to increase your risk of a severe asthma attack during childbirth. In fact, asthma usually improves during labor and delivery.

Your Baby's Health

Asthma attacks can lower blood flow and oxygen to your baby, which can lead to complications before and after birth and even life-long health issues, including:

Uncontrolled asthma during pregnancy may increase the risk of infant death, premature delivery, or low birth weight by between 15% and 20%.


If your asthma symptoms seem to be worsening, discuss it with your obstetrician, allergist, and pulmonologist.

Pregnancy can affect breathing to some degree, so your doctor will perform spirometry to determine whether symptoms are normal pregnancy-related issues or worsening asthma. Tests will focus on vital and total lung capacity, which are not usually affected during pregnancy.

Asthma may be newly diagnosed during pregnancy. But in those cases, women typically had asthma previously—the condition had just gone undiagnosed.

Asthma is not brought on by pregnancy or body changes associated with pregnancy.

If you've never had asthma before and have new breathing problems during pregnancy, talk to your doctor right away. People who are newly diagnosed with asthma during pregnancy are 2.7 times more likely to experience asthma exacerbations, including hospitalization.

To determine whether you have asthma, your doctor will:

  1. Examine you for common asthma symptoms: wheezing, cough, chest tightness, shortness of breath.
  2. Measure airflow in your lungs and determine whether any decreased airflow improves spontaneously or with treatment.


The first course of asthma treatment for pregnant women is to avoid triggers that cause the immune system to overreact and spark an asthma attack. The most common triggers are:

The next step is to control symptoms with medication. In general, doctors aren't likely to prescribe a new asthma medication during pregnancy. Rather, your asthma plan will probably include the same drugs you used pre-pregnancy unless there's a compelling reason to switch.

Some women avoid taking asthma medications during pregnancy for fear that they may harm the baby, leading to asthma symptoms worsening. But asthma itself is a greater risk to fetal development than the side effects of asthma medications.

Medication Risks During Pregnancy

A long-term study found that asthma medication use during pregnancy doesn't raise the risk of most birth defects. However, researchers say it might increase the risk of some, including:

  • Atresia: Lack of a proper opening in the esophagus or anus
  • Omphalocele: Internal organs protruding through the belly button

However, they couldn't determine whether the birth defects were related to:

  • Medication use
  • Asthma itself
  • Other conditions common in people with asthma

Even if the medications are to blame, the risks of uncontrolled asthma still appear to be higher than those tied to use of these drugs.

In a study published in 2020, researchers recommended an electronic system to notify doctors when their pregnant patients with asthma go more than four months without filling a prescription for this very reason.

Pregnancy Risk Categories

The U.S. Food and Drug Administration (FDA) ranks medications according to their risk during pregnancy:

  • A: No evidence of risk after adequate studies in humans
  • B: No evidence of risk in animal studies; no adequate studies in humans
  • C: Animal studies have a demonstrated risk; no adequate studies in humans; potential benefits may outweigh risks in some cases
  • D: Evidence of risk in human babies; potential benefits may outweigh risks in some cases
  • X: Evidence of risk in animals or humans; risks involved clearly outweigh potential benefits

Current asthma medications fall into categories B or C. Even among those in the same category, though, some are chosen over others due to other factors such as side effects or dosing challenges.

 Drug Class Drug Category Use in Pregnancy 
Short-acting beta-agonists (SABAs) terbutaline
B Preferred; controversial when used alone
C Preferred; controversial when used alone
Long-acting beta-agonists (LABAs) formoterol
C Preferred
Inhaled corticosteroids (ICSs) budesonide B First-line treatment (preferred over other ICSs)
C Preferred, first-line treatment
C With caution
Oral corticosteroids methylprednisolone
C With caution
ICS+ LABA budesonide/fomoterol
C Preferred
Leukotriene modifiers montelukast
B Preferred when started pre-pregnancy
  zileuton C With caution due to liver side effects
Anticholinergics ipratropium B Preferred as add-on for severe attacks
Anti-IgE medications (monoclonal antibodies) omalizumab B With caution; shouldn't be started during pregnancy
Methylxanthines theophylline C With caution
Mast-cell stabilizers cromolyn C With caution
Source: Prescribers' Digital Reference

Preferred Medications

Most doctors recommend inhaled asthma medications during pregnancy because they target the source of asthma symptoms and very little medication crosses the placenta. Several classes of medications are considered safe during pregnancy, at least in some circumstances.

Inhaled corticosteroids are considered the first-line treatment and are the drugs most often used during pregnancy, followed by beta2 agonists.

Inhaled Corticosteroids (ICS)

While studies are unclear on whether the inhaled form of these drugs increases birth-defect risk, they may carry a modest risk increase for cleft lip or palate.

Research shows the risk of low birth weight is higher in those with asthma who don't take these drugs during pregnancy. (However, not all drugs in this category are considered safe during pregnancy.)

Beta2 Agonists

These SABAs and LABAs, and some controversy exists about their safety during pregnancy. Salbutamol is considered the safest SABA while salmeterol is considered the safest LABA.

Some experts argue against using SABAs alone during pregnancy because they don't prevent asthma attacks, which put your baby in danger.

Other Preferred Drugs

Many other drugs may be continued during your pregnancy, but they may not be the best option for everyone. These include:

  • Anticholinergics: While these drugs appear safe, little research has been done with regard to pregnancy.
  • Theophylline and cromolyn: No association between these drug and birth defects has been found. However, they may cause unpleasant side effects and interact negatively with other medications.
  • Leukotriene receptor agonists (LTRAs): These drugs are only recommended if you took them before getting pregnant. An exception is zileuton, which isn't recommended during pregnancy because of liver-related side effects.
  • Allergen immunotherapy (AIT): This treatment can often be continued during pregnancy. It's not clear whether it's safe to start it during pregnancy, though.

Non-Preferred Medications

Some inhaled corticosteroids cross the placenta in high concentrations and pose a risk.

Corticosteroids not recommended during pregnancy include dexamethasone, betamethasone, and oral prednisone because they're associated with higher rates of birth defects.

Omalizumab shouldn't be started during pregnancy because the dosage is weight-dependent, which presents a problem with the rapid weight gain of pregnancy.

Does Your Treatment Need a Change?

Your asthma is considered poorly controlled if your asthma symptoms:

  • Are present more than two days per week
  • Wake you up more than two nights per month

At this point, your baby's at risk for reduced oxygen and the associated problems. Talk to your doctors about adjusting your treatment plan so you can properly manage the condition.

A Word From Verywell

About one-third of people with asthma who get pregnant will have more severe symptoms during pregnancy. Another third will experience less severe symptoms, and the final third will have no change in symptoms. You can't be sure where you'll fall in this mix, so it's vital that you continue to see your asthma specialist throughout your pregnancy, have your asthma monitored, and follow your treatment regimen.

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