Anemia caused by acute blood loss Anemia of inflammation or malignancy Megaloblastic anemia 0.030 ..••. Anemia cutoff for c 0.025 0 (12.0 g/dL) : ..... Anemia cutoff for 0 0.020 . (1 1.0 g/dL) 0.015 : 0.010 0.005 04.06.0 8.010.0 18.0
FIGURE 56-2 Global trends in hemoglobin concentrations in pregnant and nonpregnant women. (Reproduced with permission from Stevens GA, Finucane MM, De-Regil LM, et al: Global, regional, and national trends in haemoglobin concentration and prevalence of total and severe anaemia in children and pregnant and nonpregnant women for 1995-201o1: a systematic analysis of populationrepresentative data, Lancet Glob Health. 2013 Jul;1(l):e16-25.)
Women whose hemoglobin concentration was three standard deviations above the mean at 12 or 18 weeks' gestation had a 1.3-to 1.8-fold greater incidence of fetal-growth restriction. Placental weight correlates negatively with maternal hemoglobin concentration (Larsen, 2016). hese indings have led some to the illogical conclusion that withholding iron supplementation to cause iron-deiciency anemia will improve pregnancy outcomes (Ziaei, 2007).
The two most common causes of anemia during pregnancy and the puerperium are iron deiciency and acute blood loss. In a study of more than 1300 women, 21 percent had thirdtrimester anemia, and 16 percent had iron-deiciency anemia (Vandevijvere, 2013). In a typical singleton gestation, the maternal need for iron averages nearly 1000 mg. Multifetal gestational requirements are considerably higher (Ru, 2016). hese amounts exceed the iron stores of most women and result in iron-deiciency anemia unless supplementation is given.
Iron deficiency is often manifested by an appreciable drop in hemoglobin concentration. In the third trimester, additional iron is needed to augment maternal hemoglobin and for transport to the fetus. Because the amount of iron diverted to the fetus is similar in a normal and in an iron-deicient mother, the newborn of a severely anemic mother does not sufer from irondeiciency anemia. Neonatal iron stores are related to maternal iron status and to timing of cord clamping.
Classic morphological evidence of iron-deiciency anemia is erythrocyte hypochromia and microcytosis (Fig. 56-3). This may be less prominent in the pregnant woman. Serum ferritin levels are lower. And, levels of hepcidin-the master regulator of iron availability-are decreased normally in pregnancy. With iron deiciency, hepcidin levels follow those of serum ferritin (Camaschella, 2015; Koenig, 2014).