When a neonate presents with anemia, the first diagnostic thought of the clinician is not of a congenital aplastic disorder. Indeed, compared with adults, all newborns normally are relatively “anemic” during a window of one to two months postpartum, the so-called physiologic anemia of the newborn. Thereafter, erythropoiesis will be stimulated, and higher hemoglobin levels are achieved. However, persistence of anemia beyond this period signals a pathologic condition. When one encounters an anemic baby whose work-up reveals no evidence of hemolysis, a negative Coombs' test, and a low reticulocyte count, with or without additional cell lines depressed, then a work-up that considers the common infectious etiologies, as well as the less common genetic causes of hypoplastic anemia, must be undertaken.

Causes of cytopenias

Aside from the physiological anemias discussed in Chapter 4, any or all of the blood-cell lines in the neonate may be affected by primary or secondary causes. The clinical picture, including historical and physical findings, will provide clues as to the etiology of the cytopenias (as discussed in Chapter 3), but often only time will allow identification of the ultimate cause of the cytopenias. Table 5.1 lists the causes of hypoplastic anemia in the newborn.

Infections

Typically, congenital infections in the neonate cause hemolytic anemias. However, some viruses can have a suppressive effect on the bone marrow.