During pregnancy, there is increased vascularity of the enlarging uterus with the interposition of uteroplacental circulation.
Principal blood changes during pregnancy -
Non pregnant Pregnancy Changes
near term
Blood volume (ml.) - 4000 5500 + 30-40 %
Plasma volume (ml.) - 2500 3750 + 40-50 %
Red cell volume (ml.) - 1400 1750 + 20-30 %
Total hemoglobin (gm) - 475 560 + 18-20 %
Hematocrit (whole body) - 38 % 32 % Diminished
Important -
Que.- Why the high volume of blood is required in pregnancy ?
Ans.- A higher circulating volume is required for the following functions -
Principal blood changes during pregnancy -
Non pregnant Pregnancy Changes
near term
Blood volume (ml.) - 4000 5500 + 30-40 %
Plasma volume (ml.) - 2500 3750 + 40-50 %
Red cell volume (ml.) - 1400 1750 + 20-30 %
Total hemoglobin (gm) - 475 560 + 18-20 %
Hematocrit (whole body) - 38 % 32 % Diminished
Important -
- There is increase in plasma volume which reduce the viscosity of blood and improves capillary blood.
- As increase in plasma volume is greater than that of red blood cell mass, hemodilution occurs. It is characterized by a lowered RBC count and hemoglobin level.
Que.- Why the high volume of blood is required in pregnancy ?
Ans.- A higher circulating volume is required for the following functions -
- To provide extra blood flow for placental circulation.
- To supply the extra metabolic needs of the fetus.
- To provide extra perfusion of kidney and other organs.
- To compensate for blood loss at delivery.
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