There are significant changes in the cardiovascular system during pregnancy (Blanchard and Shabetai, 2004; Monga, 2004; McAnulty et al., 2008). The total blood volume increases steadily during the first trimester and it is increased by almost 50% by the 30th gestational week without any further change in the last weeks of pregnancy. Between 8th and 32nd gestational week, plasma volume increases more intensively (up to 45%) than red blood cell mass (25%). This explains the common “physiologic” anemia of pregnancy, which without iron supplementation may result in low hematocrit (about 33 ml/dL) and hemoglobin (11 g/dL) values.