Dyspnea

What is dyspnea during pregnancy?

Dyspnea is the medical term for difficulty breathing. There are hundreds of different causes of dyspnea, consisting of a plethora of diseases and injuries. We cannot cover all such conditions in this report. Still, its appropriate to present an overview of causes and the context of dyspnea in the setting of pregnancy and the post-partum period when you are nursing. For women in their reproductive years, who are pregnant, causes of dyspnea that need to be recognized immediately in particular as they are dangerous and can begin during pregnancy include pulmonary embolism (PE) and a handful of cardiovascular conditions, namely acute coronary syndrome (ACS), peripartum cardiomyopathy (PPCM), and aortic dissection. There are also chronic conditions that can change during pregnancy, such as asthma. Plus, there are conditions that can increase demand on your heart and lung function, namely anemia, of which there are many types, but one type, iron deficiency anemia, is fairly common in pregnancy. Less common are neurological conditions that can cause breathing difficulty. Additionally, a pregnant woman (just like a non-pregnant person) can suffer a chest injury, resulting in a pneumothorax (air in the chest cavity), causing the lung to collapse.

The most common cause of dyspnea during pregnancy is the normal physiological changes of pregnancy. In addition to the volume of blood increasing, notably, the changes include a rearrangement of the positions of the contents of your abdominal cavity as the womb grows. This, in turn, pushes the diaphragm upward, shrinking the chest cavity, which interferes with lung function. Consequently, it is very normal to feel dyspnea during pregnancy, a fact that complicates the evaluation of dyspnea in a pregnant woman.

How common is dyspnea during pregnancy?

The occurrence of dyspnea increases as pregnancy advances. About 50 percent of pregnant women complain of dyspnea by the 19th gestational week and 76 percent by the 31st week.

How is dyspnea during pregnancy diagnosed?

First of all, your vital signs will be checked constantly, including your breathing rate, pulse oximetry, heart rate, and blood pressure – all of which are relevant to dyspnea and its underlying causes. Dyspnea is not a diagnosis, but a symptom that, together with other symptoms, can alert your doctor to the need to work you up to find the underlying problem. Diagnosis of anemia, for instance, requires a simple blood test, while the evaluation of asthma involves pulmonary function testing.

While your dyspnea may be the result of the normal changes of pregnancy, causing the diaphragm to shift upward, testing is needed to rule out life-threatening conditions such as PE and other cardiovascular conditions. Doctors can then check for a PE with a procedure called ventilation/perfusion (V/Q) scanning, which analyzes air flow using a radioactive substance. Another method for diagnosing PE is computed tomographic pulmonary angiography (CT-PA). Some pulmonary specialists prefer using simple flat x-ray scans (CXR) instead of CT-PA to minimize the radiation dose to the fetus, although CT-PA is a better test for detecting PE. Since PE is an emergency that can be fatal quickly both to the mother and fetus, concern about scanning radiation is not appropriate.

Evaluation for acute coronary syndrome includes checking your blood for cardiac enzymes and cardiac muscle proteins (which leak out of the myocardium when it is damaged) and performing electrocardiography (ECG). When you have an ECG, numerous electrodes will be placed on different locations of your body. This provides doctors with signals of the hearts electrical activity through the heart at different angles and directions. This is visualized in what are called ECG leads, and by measuring ST elevation, T wave depression, and other abnormalities in the different leads, doctors can hone in on the location of the artery problem. Subsequently, there are more specialized procedures that can be performed to locate the problem and to determine its severity and whether it requires immediate invasive treatment, such as percutaneous coronary intervention (PCI), or, in severe cases, open-heart surgery.

In assessing for possible aortic dissection, on physical examination, the doctor may find whats called a wide pulse pressure, meaning that the difference between the systolic and diastolic pressure is unusually high. There also may be a noticeable difference in blood pressure of the left and right arms. On chest x-ray, the aorta often looks wider than it should, but the diagnosis of AD requires more sensitive imaging procedures. The main such procedures used are computed tomography (CT) scanning, magnetic resonance imaging (MRI), and transesophageal echocardiography (TEE), which is a special kind of ultrasound taken from a probe inserted down the esophagus to a level that is next to the heart and aorta.  

Diagnosis of PPCM depends on chest x-ray (CXR), electrocardiography (ECG, which measures electrical activity in the heart from different directions), an echocardiogram, a stress test on a treadmill, and a range of other tests that may include cardiac magnetic resonance imaging (MRI), cardiac catheterization in which instruments are passed into your heart through a tube inserted through a vein in your leg, and various blood tests and genetic tests. A diagnosis of PPCM can be made if you meet three criteria: heart failure beginning any time from a month before delivery until 5 months after delivery; an ejection fraction below 45 percent as measured during echocardiography (normal ejection fraction ranges from 55 to 70 percent and often is far above 70 percent in trained athletes); your physicians are able to rule out other possible causes of the low ejection fraction and heart failure.

Does dyspnea cause problems during pregnancy?

Dyspnea is a sign that some aspect of your cardio-pulmonary system is not meeting either your need for oxygenation or the removal of carbon dioxide from your body. Problems caused by dyspnea depend on the underlying cause. With certain conditions, such as anemia, a lack of oxygen in your blood may cause you to hyperventilate, leading to a condition called respiratory alkalosis, which can harm you in multiple ways. On the other hand, if your breathing difficulty is due either to decreased ability to stimulate breathing, such as in certain neurological disorders or to obstructive pulmonary disease such as asthma, you can develop whats called respiratory acidosis. This is the opposite of respiratory alkalosis but also is not good. In both cases, your acid-base balance and electrolyte balance is disrupted. This can lead to complications with multiple organ systems.

Furthermore, if you cannot get adequate amounts of oxygen to critical tissues, organs can malfunction. This includes very critical organs, such as the brain and heart. With some chronic respiratory conditions, particularly asthma in pregnancy, they can have a range of effects that can be positive or negative. With asthma, roughly one-third of patients worsen with pregnancy, but another third remain the same, while another third improve in pulmonary function.

Does dyspnea cause problems for the baby?

Consequences for the baby depend on whether your dyspnea is part of a severe underlying disease that worsens with pregnancy or is simply the result of normal physiological changes of pregnancy. If your dyspnea is part of a disease that is worsening as the pregnancy progresses, there
is an increased risk of low birth weight, reduced fetal growth, and fetal death.

What to consider about taking medications when you are pregnant or breastfeeding:

• The risks to yourself and your baby if you do not treat the dyspnea
• The risks and benefits of each medication you use when you are pregnant
• The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat dyspnea during pregnancy?

As with various other questions and issues addressed earlier, medication issues depend greatly on which condition is causing the dyspnea. With some conditions, you might need medications to open up blood vessels, to slow and strengthen the heartbeat, or heparin or other agents to break up clots, such as in the case of a PE. There are particular categories of drugs that are contraindicated during pregnancy as they can harm the fetus, notably a group of cardiovascular medications called angiotensin-converting enzyme (ACE) inhibitors, which can damage the fetal kidney. Whatever the cause, if you have a serious medical condition while you are pregnant, you will be overseen by a specialist in maternal-fetal medicine or an obstetrician who specializes in high-risk pregnancies. Depending on your condition, there will also be various specialists involved, such as a cardiologist or a pulmonologist.

Who should NOT stop taking medication for dyspnea during pregnancy?

The need for medication and the type of medication varies greatly depending on the underlying condition.

What should I know about choosing a medication for my dyspnea during pregnancy?

It is important to stay in communication with your health care provider as the release of new studies over time can change the outlook on the role of specific medications during pregnancy.

You may find Pregistrys expert reports about the medications to treat this condition here. Additional information can also be found in the sources listed below.

What should I know about taking a medication for my dyspnea when I am breastfeeding?

As noted earlier, there are numerous conditions that can cause dyspnea during pregnancy, but there is a particular concern about PE. This is not only because PE can be quickly life-threatening, but also because it can strike in any pregnant woman who is otherwise in good health simply because she suffered a venous thrombosis (blood clot in a deep vein), due to the changes occurring in the body with pregnancy. In such cases, the mainstay treatment is the drug heparin. This can mean low molecular weight heparin (LMWH) or in some cases, unfractionated heparin (UFH). Neither UFH nor LMWH is thought to be harmful in breastfeeding. On the other hand, if you have suffered ACS or an asthma attack, or if you have PPCM or another severe cardiovascular condition, you are likely to be on various medications, some of which may require you to avoid breastfeeding.

What alternative therapies besides medications can I use to treat my dyspnea during pregnancy?

As noted at the beginning, very often, dyspnea during pregnancy is simply a result of normal physiological changes. When dyspnea is the result of severe underlying cardiac or pulmonary disease, you need medication. On the other hand, there are other conditions, such as iron deficiency anemia, that can cause dyspnea and for which the treatment is something other than medication. With iron deficiency anemia, for instance, the treatment is supplemental dietary iron.

What can I do for myself and my baby when I have dyspnea during pregnancy?

It is very important to have a complete medical evaluation to determine the cause of your dyspnea.

Resources for dyspnea in pregnancy:

For more information about dyspnea during and after pregnancy, contact http://www.womenshealth.gov/ (800-994-9662 [TDD: 888-220-5446]) or contact the following organizations:

• Mayo Clinic. Pregnancy and Asthma 
• Cleveland Clinic. Dyspnea.