Expiratory reserve volume in pregnancy...

• A. Increases
• B. Decreases
• C. Remains unchanged
• D. Varies with activity

Answer: (B)

During pregnancy, the expanding uterus pushes the diaphragm upward, changing chest wall mechanics. Expiratory reserve volume is the amount of air you can forcibly exhale after a normal exhalation. With the diaphragm elevated, there’s less elastic recoil space and a reduced capacity to exhale beyond a normal breath, so the ability to expel extra air decreases. This occurs even though tidal volume and overall minute ventilation rise to meet increased oxygen needs. Therefore, expiratory reserve volume decreases in pregnancy.