The respiratory system is made up of the organs involved in the exchange of oxygen and carbon dioxide. Its main job is to move fresh air (oxygen) into your body and move waste gases (carbon monoxide) out of your body. The system includes:

• Nose
• Throat (pharynx)
• Voice box (larynx)
• Windpipe (trachea)
• Lungs, which contain:
  • Airways (bronchi)
  • Smaller airways (bronchioles)
  • Tiny airways (alveoli)

The lungs are a pair of cone-shaped organs made up of spongy, pinkish-gray tissue. They take up most of the space in the chest (thorax). The lungs are surrounded by a membrane called the pleura. The lungs are divided into sections called lobes.

When you breathe, the air:

• Enters the body through the nose or the mouth
• Travels down the throat through the larynx and trachea
• Goes into the lungs through the bronchi:
  • Then bronchi divide into bronchioles
  • Bronchioles end in the alveoli

The gas exchange takes place between the alveoli and nearby blood vessels.

Because of pregnancy hormones and the growing fetus, many changes happen in the respiratory system. Some changes include:

• Stuffy or runny nose and nosebleeds
• Chest increases in size
• Diaphragm, the large flat muscle used in breathing, moves upward toward the chest
• Increase in the amount of air breathed in and out
• Decrease in amount of air the lungs can handle
• Increase in oxygen use

Because of these changes, many pregnant people feel short of breath or have some trouble breathing. Shortness of breath commonly starts during the first or second trimester. The frequency tends to increase during the second trimester and stabilize during the third trimester. If you have a lung condition, such as asthma, before pregnancy, you may need to change treatment to control symptoms and prevent complications.