Causes of Anemia During PregnancyDuring pregnancy, the demand for iron and other vitamins is increased. In order to have enough red blood cells for the fetus, the body starts producing more red blood cells and plasma. It has been calculated that the blood volume increases approximately 50% during pregnancy, although the plasma increase is disproportionately greater. This causes a dilution of the blood, making the hemoglobin concentration fall. This is a normal process, with the hemoglobin concentration at its lowest between weeks 25 and 30. Other causes of anemia in pregnancy include:Vegetarian diet with less greensLack of iron in dietLack of folic acid in dietLack of vitamin B12Loss of blood due to bleeding (from malaria, hook-worm infection, hemorrhoids or stomach ulcers) Published on Aug 27, 2010Last Updated on Jul 11, 2019