**2. First Pilar: enlargement of red blood cell mass**

During pregnancy, physiological changes take place and prepare the woman in several ways, especially for the delivery moment and prevention of blood loss at this time. One of them is the hematological system, where maternal plasma volume expansion reaches a net increase of approximately 50% by 34 weeks' gestation. Red *Patient Blood Management in Cesarean Section DOI: http://dx.doi.org/10.5772/intechopen.110331*

blood cells rise to 30% above the pre-pregnancy level at term due to an increased concentration of erythropoietin and the erythropoietic effect of progesterone, prolactin, and placental lactoge [5, 6].

The difference in the increase in blood elements results in hemodilution, which is known as physiologic anemia of pregnancy. Despite the hemodilution, the rheological changes ensure enough oxygen delivery, better placental perfusion, less risk for thrombosis, despite the bleeding that occurs with childbirth, the objectives being to improve the main outcome of the first pillar [5, 6].

At the same time, there is a substantial increase of the coagulation factors I, VII, VIII, IX, X, and XII and von Willebrand factor. Furthermore, there is a decrease of Factor XI and XIII and a physiologic decrease of protein S, while F II and V do not change, resulting in an accelerated but compensated intravascular coagulation state [6].

The main objective of patient blood management strategies in pregnancy is to prevent postpartum hemorrhage (PPH) and decrease morbi-mortality associated with blood products transfusion. Thus, the first step is to recognize risk factors, so women with previous PPH in the last pregnancy, pre-existing anemia, prior cesarean section, multiple gestations, uterine fibroma, preeclampsia, obesity, chorioamnionitis, and fetal macrosomia are at increased risk for PPH [7, 8].

However, almost 61% of women with PPH do not have a risk factor, excluding maternal age and cesarean section. Therefore, we have to consider that all pregnant women have a considerable risk for PPH [7, 8].

From all of the possible risk factors, anemia and iron deficiency are susceptible to modification, and this is where the first pillar of the PBM could be specifically implemented. Pregnant women are the only patients in whom we can detect iron deficiency and anemia long before a potential blood loss at delivery [5].

Anemia affects approximately 40% of pregnant women worldwide with iron deficiency as main cause. Anemia has been associated with several complications like the need for increased health care requirements, intensive care for both the mother and neonate, higher rates of preeclampsia, higher rates of induction of labor, cesarean delivery, blood transfusion and higher rates of infectious disease for both mother and newborn, all of these anemia severity – dependent, increasing maternal y perinatal morbidity and mortality [7, 9, 10].

Anemia treatment has the potential to improve outcomes for affected women and their fetuses and neonates and minimize the illness burden and cost due to this common disease [9].

Once the diagnosis of anemia is done, we have to evaluate the cause of the disease, starting with iron metabolism analysis because it is responsible for 60% of anemia cases. In pregnancy, iron requirement increases considerably, and mother's stores cannot fulfill this need most of the time. Therefore, all guidelines of obstetric care recommend a complete hematological investigation when a low hemoglobin value is detected including transferrin level, iron saturation and supplementation with iron o B12 if needed [5, 10].

Iron metabolism evaluation must be done with ferritin screening (30 – 100 ng/ ml as normal cutoff) where values below 30 ng/ml mean clear iron deficiency, even with normal hemoglobin, as it is the best and most practical marker for iron store evaluation. Nevertheless, serum ferritin is also an acute-phase protein, so this value increases during infectious or inflammatory episodes. It is recommended to measure the C – reactive Protein (CRP) levels with normal ferritin in case of low Hb in inflammatory situations [5, 10, 11].

Other markers we can evaluate for iron deficiency are red cell distribution width (RDW) and mean corpuscular hemoglobin (MHC). Transferrin saturation rate is a

marker that shows us the percentage of iron binding sites that are occupied. The normal values are between 20 and 50%, where levels below 20% mean iron deficiency [5, 10].

WHO recommends routine iron supplementation for every pregnant woman, especially in low-income countries, to prevent iron deficiency without anemia and iron deficiency with anemia with 30 – 60 mg/day of oral iron. In cases of mild or moderate anemia, it is advised to have an iron substitution of 160 – 200 mg/day. Iron supplementation usually has gastrointestinal side effects; when it is administrated during the first trimester, it can worsen nausea or gestational emesis, gastric pain, or constipation. Intravenous iron is indicated when there is intolerance to oral iron preparations or when Hb does not increase appropriately (less than 1 g/dl within 14 days) or when there is severe anemia during the third trimester or progressive anemia or if a rapid treatment is needed [5, 10, 11].

The optimal duration of iron deficiency treatment is 6–8 weeks with periodical Hb and serum ferritin screening every 4 weeks [10, 11].
