Chronic renal insuiciency is the most common disorder that we have encountered as a cause of this type of anemia during pregnancy. Some cases are accompanied by erythropoietin deficiency. As discussed in Chapter 53 (p. 1034), during pregnancy in women with mild chronic renal insuiciency, the degree of red cell mass expansion is inversely related to renal impairment. At the same time, plasma volume expansion usually is normal, and thus anemia is intensified (Cunningham, 1990).
For treatment, adequate iron stores must be ensured. Recombinant eythropoietin has been used successfully to treat anemia stemming from chronic disease (Weiss, 2005). In pregnancies complicated by chronic renal insuiciency, recombinant erythropoietin is usually considered when the hematocrit approximates 20 percent (Cyganek, 2011; Ramin, 2006). One worrisome side efect of this agent is hypertension, which is already prevalent in women with renal disease. Red cell aplasia and antierythropoietin antibodies have also reported (Casadevall, 2002; McCoy, 2008).
These anemias are characterized by blood and bone-marrow abnormalities from impaired DNA synthesis. This leads to large cells with arrested nuclear maturation, whereas the cytoplasm matures more normally. Worldwide, the prevalence of megaloblastic anemia during pregnancy varies considerably. It is rare in the United States.
Megaloblastic anemia developing during pregnancy almost always results from folic acid deficiency. In the past, this condition was referred to as pernicious anemia of pregnancy. It usually is found in women who do not consume fresh green leay vegetables, legumes, or animal protein. As folate deficiency and anemia worsen, anorexia often becomes intense and further aggravates the dietary deiciency. Drugs and excessive ethanol ingestion either cause or contribute (Hesdorfer, 2015).
In nonpregnant women, the folic acid requirement is 50 to 1 00 �g/ d. During pregnancy, requirements are increased, and 400 �g/ d is recommended. he earliest biochemical evidence is low plasma folic acid concentrations (Appendix, p. 1255). Early morphological changes usually include neutrophils that are hypersegmented and newly formed erythrocytes that are macrocytic. With preexisting iron deiciency, macrocytic erythrocytes cannot be detected by measurement of the mean corpuscular volume. Careful examination of a peripheral blood smear, however, usually demonstrates some macrocytes. As the anemia becomes more intense, peripheral nucleated erythrocytes appear, and bone marrow examination discloses megaloblastic erythropoiesis. Anemia may then become severe, and thrombocytopenia, leukopenia, or both may develop. he fetus and placenta extract folate from maternal circulation so efectively that the fetus is not anemic despite severe maternal anemia.
For treatment, folic acid is given along with iron, and a nutritious diet is encouraged. By 4 to 7 days after beginning folic acid treatment, the reticulocyte count is increased, and leukopenia and thrombocytopenia are corrected.