The Bottom Line

A feeling of shortness of breath, or that a woman “cannot catch her breath”, has many possible normal and expected causes during pregnancy and can start very early.

Women can be surprised at how fast this symptom presents, mostly due to the immediate respiratory, cardiac, metabolic, and hormonal changes that occur in the first few weeks. 

To combat this symptom as pregnancy progresses, women should stay hydrated and exercise regularly* (if cleared) which improves shortness of breath, even early in the first trimester.

*The above is only true if the experienced shortness of breath is not due to an underlying medical condition. Women should always be cleared by their HCP prior to starting any exercise regimen during pregnancy.

Although exercise may seem like the worst thing to do when experiencing breathlessness, it is theorized that light to moderate physical activity may help the body adjust to early fatigue and cardiac changes, as well the early increase in blood volume by improving circulation.

However, despite its normalcy, women who have severe and/or sudden shortness of breath, along with swelling and/or chest pain need to seek immediate medical care, as shortness of breath plus these symptoms are strong indications of potentially very serious complications – although these are rare. In this scenario, exercise is not advised.

If women are experiencing moderate, gradual shortness of breath that is bothersome or concerning, they should call their health care provider (HCP) for an assessment. Fatigue, dehydration, and some nutritional deficiencies can also cause shortness of breath during pregnancy.

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Shortness of breath, known as dyspnea, results in women breathing very fast as if they need to “catch their breath”. This shortness of breath, or breathlessness, can occur very early in pregnancy and is not dependent on the heavy weight of the uterus and/or baby, but by other pregnancy-related changes as well (i.e. it also happens in the first trimester).

Up to 70% of pregnant women may experience breathing-related discomfort early in pregnancy, even from normal everyday activities such as walking, climbing stairs, and performing regular household-related tasks.

This symptom can be both scary and surprising for women and can puzzle their HCP. Shortness of breath is a very common symptom of pregnancy in general, but it is also a first “red flag” symptom for other serious conditions. Fortunately, these conditions are rare, but HCPs may want to assess a pregnant woman who complains of moderate to severe shortness of breath to rule out all other possibilities.

Causes – Early Pregnancy

The exact physiological reasons women experience shortness of breath during pregnancy are not completely understood. However, early in pregnancy, the uterus/fetus are not yet adding pressure to the respiratory system, therefore, the only other major contributing factors are hormones (progesterone and estrogen).

It is frequently reported that the rise of progesterone in the first trimester causes pregnant women to breathe faster, leaving women “short of breath”; however, this is debated, as some research indicates the respiratory rate of pregnant women remains unchanged throughout gestation.

Despite the above, pregnancy is associated with an increase in the amount of oxygen breathed in and out. Women may be trying to adjust to an increased oxygen requirement assessed to occur almost immediately after implantation.

Cardiac output is also increased during pregnancy, meaning it takes less work to create a faster heart/breathing rate than prior to pregnancy. More than 50% of the change in cardiac output takes place before 8 weeks of pregnancy.

Total blood volume during pregnancy increases by about 1.5 liters (almost 40 to 50% increase) to support fetal and placental development and protection from blood loss during delivery. This expansion includes additional red blood cells which carry oxygen throughout the body, and their increase requires women to have enough iron stores.  All these factors can cause signs and symptoms such as shortness of breath, fatigue, swelling, dehydration, and anemia (lack of red blood cells).

Blood volume increases gradually from 6 to 20 weeks of pregnancy and reaches a maximum volume around 32 to 34 weeks.  Around 20 weeks, women may begin to overcome the early adjustments and feel more energetic and less short of breath.

Anemia is a common cause of more gradual onset of breathlessness and fatigue during pregnancy. It can also be caused by a shortage of folic acid or vitamin B12, all required for making red blood cells. Some women may be able to take supplements of either of these vitamins if iron supplements do not work or cause adverse side effects.

Organogenesis, the period in the first trimester during which most of the fetal organs develop, requires a significant amount of energy from the mother.  It is theorized this also leads to fatigue, which causes women to sleep and nap more often. However, research indicates that rest exacerbates shortness of breath, while physical exercise may improve it. 

Note: It can be very difficult for women to balance feelings of fatigue and shortness of breath and deciding between rest and/or physical exercise. This is further compounded and worsened for women who also experience nausea and vomiting of pregnancy at the same time.

Causes – Late Pregnancy

Later in pregnancy, the uterus grows larger and can press against the diaphragm, which decreases lung capacity. This results in some women feeling like it may be difficult to breathe, especially while sleeping.  Although this experience is disconcerting, research shows women with this symptom at this stage of pregnancy are still getting enough oxygen.

Breathing difficulties are usually relieved near term as the baby settles deeper into the pelvis. The top height of the uterus drops, allowing the diaphragm to return back down a few centimeters.

Causes – Serious Conditions

Whenever a pregnant woman complains of shortness of breath, an HCP will assess other possible signs and symptoms to rule out potentially serious complications, no matter how unlikely

After these are ruled out, an HCP can be more comfortable with the finding the symptom is only due to normal pregnancy-related changes.  This physical assessment is important as women are increasingly becoming pregnant with co-existing diseases (i.e. respiratory, cardiac, metabolic).

Although serious complications that present with shortness of breath are rare, it is always a good idea for a pregnant woman to be evaluated by her HCP, especially if other symptoms are present (see below).

Shortness of breath is the most common presenting symptom of women suffering from cardiac or respiratory failure, pulmonary embolism, or deep vein thrombosis.  Non-pregnancy-related conditions that can also cause shortness of breath include heart attack, allergic reaction, or pulmonary edema (severe fluid overload).

HCPs will run routine blood and imaging tests to rule out these more serious conditions, which generally present with severe and sudden shortness of breath, and may be accompanied by other symptoms such as chest pain and/or swelling, which requires immediate medical attention.


Shortness of breath is very common during pregnancy and can be considered completely normal and expected. However, in rare instances, it may also be the first symptom of something more severe.


If women experience any of the following, it is considered a medical emergency and they need to seek immediate care:

  • Severe and/or sudden shortness of breath

  • Difficulty talking in full sentences

  • Chest pain

  • Swelling in the face or abdomen

  • Heart palpitations

  • A rapid pulse

  • Fever and/or chills

For "normal" shortness of breath, pregnant women are advised to stay hydrated in order to support the growing amount of both blood volume and amniotic fluid, as well as to combat fatigue and dehydration. Preventing these conditions can alleviate feelings of breathlessness.

During an "episode", women should also try to sit or stand up straight and lift their arms over their head to expand the lungs, and breathe calmly and slowly through the nose and out the mouth.

Women should try to relax and avoid panicking which could lead to further hyperventilation; women should also find someone who can assist them if necessary, especially if any of the above symptoms are also present.

If women experience shortness of breath during exercise, they need to immediately stop, rest, and call their HCP if necessary (or if symptoms do not resolve).

Women should read the below related articles to expand their knowledge on the above topic:

Women should also consider sharing and submitting their experience below regarding shortness of breath during pregnancy.


Watching a pregnant women look like she cannot catch her breath can be very disconcerting; however, most of the time, this symptom is normal during pregnancy and will pass as she slowly rests and breathes slowly.

A woman’s partner/support should try to get her to take slow, deep breaths if possible, and engage in conversation to assess if she is in any further distress.

Partners/support should pay attention, know the woman's “normal”, and understand signs of actual, true distress if the woman cannot express it herself, and be prepared to act if necessary.


Dyspnea and Palpitation during Pregnancy (Korean J Intern Med, 2001)


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