How does plasma volume change during pregnancy?

How does plasma volume change during pregnancy?

• A. Increases 45% by term
• B. Increases 15%
• C. Decreases 10%
• D. Increases 60%

Answer: (A)

Plasma volume expands substantially during pregnancy to support the growing uterus and placenta and to maintain adequate perfusion despite vascular changes. This expansion begins early and continues into the third trimester, outpacing the rise in red blood cell mass. The result is a large increase in circulating plasma, which also causes the blood to become relatively more diluted—leading to the mild anemia often seen in pregnancy, which is normal. This substantial increase by term is the reason the correct choice stands out as the best answer. Choices suggesting only a small increase, a decrease, or an exceptionally large rise don’t reflect the typical physiologic pattern seen in pregnancy.

Plasma volume expands substantially during pregnancy to support the growing uterus and placenta and to maintain adequate perfusion despite vascular changes. This expansion begins early and continues into the third trimester, outpacing the rise in red blood cell mass. The result is a large increase in circulating plasma, which also causes the blood to become relatively more diluted—leading to the mild anemia often seen in pregnancy, which is normal.

This substantial increase by term is the reason the correct choice stands out as the best answer. Choices suggesting only a small increase, a decrease, or an exceptionally large rise don’t reflect the typical physiologic pattern seen in pregnancy.