Читать книгу Protocols for High-Risk Pregnancies - Группа авторов - Страница 125

During a singleton gestation, plasma volume doubles (increasing approximately 1000 mL) and red blood cell (RBC) volume increases by 25% (300 mL), with RBC production lagging slightly behind plasma expansion. This results in a physiological dilutional anemia of pregnancy, which reaches a nadir during the late second to early third trimester (Table 11.1). The Centers for Disease Control and Prevention (CDC) define anemia as a hemoglobin (Hb) below the fifth centile for a healthy, iron‐supplemented population. This translates to a threshold of Hb less than 11 g/dL in the first and third trimesters, and less than 10.5 g/dL during the second trimester. Rates of anemia in pregnancy vary widely between different populations and socioeconomic classes.