Final answer:
A pregnant patient's hematocrit levels typically drop due to hemodilution, which occurs because of the increased blood volume that naturally happens during pregnancy to meet the demands of the fetus.
Step-by-step explanation:
A pregnant patient's hematocrit drops during pregnancy primarily because of hemodilution. During pregnancy, there is a substantial increase in blood volume to help manage the demands of fetal nourishment and waste removal. Hematocrit levels decrease as a result of the plasma volume increasing more than the red blood cells which leads to a relative dilution of the red blood cells in the bloodstream. This physiological adaptation ensures that both the mother and the fetus receive adequate blood flow and oxygenation.