One of the five principles of yoga is pranayama, or the science of breath control. Pranayama consists of a series of exercises designed to increase the oxygen in the blood and brain and to control prana, or the vital life energy. There are four basic stages of breathing used in yoga:
Puraka is a single, smooth, continuous inhalation. If you pause one or more times during a single inhalation, it is called a "broken Puraka," rather than a series of short Purakas.
Abhyantara Kumbhaka (Pause after Inhaling)
During Kumbhaka, you stop the flow of air and hold it in your lungs without moving any muscles or parts of your body. Remember that pregnant women should not hold their breath for extended periods of time.
Like inhalation, Rechaka should be smooth and continuous. In general, you use muscular energy to inhale air, but simply relax your muscles to release it. However, you can also use muscular energy to force the air out. When you deliberately control the rate and pattern of your breathing and pauses, you should expect to exert some effort at each stage, even when in a state of complete relaxation.
Bahya Kumbhaka (Pause after Exhaling)
Kumbhaka is the pause after you exhale and is deliberate and prolonged. This empty pause completes the breathing cycle and ends when a new inhalation begins.
Pranayama is the awareness or control of the breath. During these breathing exercises, the duration of each of the three stages of breath (inhalation, retention and exhalation) is regulated in order to strengthen and cleanse the nervous system, thereby increasing your source of life energy. Pranayama helps calm and focus the mind while bringing oxygen to your and your baby's blood. At any stage of life, performing breathing exercises can help decrease stress and anxiety and increase tranquility, comfort, and confidence.