Why Do Pregnant Women Hyperventilate?

When a woman becomes pregnant, her body undergoes a series of changes to help her cope with pregnancy and protect her growing fetus. Some of those changes affect her respiratory system. As a result, pregnant women often hyperventilate.

What is hyperventilation?

Hyperventilation is very fast, deep breathing that usually results from panic or anxiety. Breathing is so rapid that the body loses too much carbon dioxide and retains too much oxygen. People who hyperventilate often feel lightheaded and short of breath. However, panic and anxiety are not the usual reasons why pregnant women hyperventilate. It has more to do with increased oxygen.

The connection between pregnancy and increased oxygen

When a woman becomes pregnant, her need for oxygen increases by as much as 20-40%. She not only has to meet her own oxygen demands, but now she has to supply enough oxygen to her fetus, placenta, and the uterus itself. This need for more oxygen is accommodated by changes in the way pregnant women breathe.

What are these changes?

As the pregnancy progresses and the uterus expands to accommodate the growing fetus, the top of the uterus (called the fundus) moves upward and pushes the diaphragm up. This puts pressure on the lungs and causes shortness of breath.

Another significant change involves the hormone progesterone. Progesterone levels increase during pregnancy so the lining of the uterus will be thick enough to nurture the fertilized egg. It also affects a woman's respiratory system by relaxing respiratory muscles and decreasing airway resistance. In addition, progesterone may make the respiratory center of the brain more sensitive to carbon dioxide, causing a pregnant woman to breathe more frequently. More breathing means more oxygen, and more oxygen helps support her, her fetus, placenta, and uterus. So mild hyperventilation is necessary to maintain the pregnancy.

How do you treat hyperventilation in pregnant women?

Although a degree of hyperventilation is necessary in pregnant women, if it becomes excessive, it should be dealt with. One of the easiest ways to treat hyperventilation in a pregnant woman is have her breathe into a paper bag. By doing this, some of the carbon dioxide she breathes out can be inhaled back in, offsetting the extra oxygen.

The pain during labor can be very difficult and cause anxiety, which could lead to more labor pains and excessive hyperventilation. Before labor, a woman should consider what type of pain management she wants during childbirth. Pharmacologic treatments include epidural anesthesia while non-pharmacologic methods include breathing techniques like those learned in Lamaze classes.

Sources:

Murray, Sharron Smith and McKinney, Emily Sloan, (2006) Foundations of Maternal-Newborn and Women's Health Nursing (5 ^th ed) , Saunders-Elsevier, Maryland Heights, Missouri, pp 115, 228, 341

WebMD, Hyperventilation, Sept 2010