Question

During pregnancy, expanding plasma volume more than RBC mass leads to a change in blood/plasma composition at a ratio of:

a) 2:1
b) 3:1
c) 4:1
d) 5:1

Answer 1

During pregnancy, the increased blood volume is predominantly due to an expansion of plasma volume rather than RBC mass, leading to a plasma to red blood cell mass ratio change of about 3:1.

Step-by-step explanation:

Changes in Blood Composition During Pregnancy

During pregnancy, the circulatory system undergoes significant changes to accommodate the needs of the developing fetus. There is a substantial increase in blood volume, exceeding preconception volume by approximately 30 percent. This increase is primarily in plasma volume, which leads to a change in the plasma-to-red blood cell (RBC) mass ratio. During pregnancy, plasma volume expands more than RBC mass, leading to a state referred to as physiological anemia of pregnancy. The specific ratio change in blood/plasma composition during pregnancy is approximately 3:1.