Which statement is true about oxygen delivery during pregnancy?

Which statement is true about oxygen delivery during pregnancy?

• A. Both minute ventilation and cardiac output decrease
• B. Cardiac output increases but ventilation decreases
• C. Both minute ventilation and cardiac output increase
• D. Both remain unchanged

Answer: (C)

During pregnancy, the body adapts to meet the fetus’s needs by increasing both the flow of blood and the amount of oxygen carried in the blood. Oxygen delivery to tissues depends on cardiac output and arterial oxygen content, and in pregnancy both rise. Cardiac output increases significantly because of greater stroke volume from expanded plasma volume and a higher heart rate, boosting the volume of oxygenated blood reaching the placenta and maternal tissues. Minute ventilation also rises due to hormonal effects (notably progesterone), leading to deeper breaths and a higher tidal volume, which enhances oxygen uptake and maintains adequate arterial oxygen content. Even though hematocrit may fall slightly from plasma expansion, the overall oxygen delivery increases because the increased cardiac output more than compensates.

During pregnancy, the body adapts to meet the fetus’s needs by increasing both the flow of blood and the amount of oxygen carried in the blood. Oxygen delivery to tissues depends on cardiac output and arterial oxygen content, and in pregnancy both rise. Cardiac output increases significantly because of greater stroke volume from expanded plasma volume and a higher heart rate, boosting the volume of oxygenated blood reaching the placenta and maternal tissues. Minute ventilation also rises due to hormonal effects (notably progesterone), leading to deeper breaths and a higher tidal volume, which enhances oxygen uptake and maintains adequate arterial oxygen content. Even though hematocrit may fall slightly from plasma expansion, the overall oxygen delivery increases because the increased cardiac output more than compensates.