Functional residual capacity during pregnancy?

• A. Increases
• B. Decreases
• C. Remains unchanged
• D. Fluctuates with breathing pattern

Answer: (B)

Functional residual capacity is the amount of air left in the lungs after a normal exhalation. During pregnancy, the growing uterus pushes the diaphragm upward, reducing the size of the chest cavity and the space available for expiration. This elevation mainly decreases expiratory reserve volume, and the net effect is a smaller volume remaining after a normal breath. Even though tidal volume increases significantly to meet higher metabolic demands, the overall functional residual capacity still falls. This reduced FRC means a smaller oxygen reserve, which can lead to quicker desaturation if ventilation is interrupted.