Sir.—The article by Philip and Tito1 in the February 1989 issue of AJDC was pleasant reading. Their finding of increased nucleated red blood cell (NRBC) counts in small-for-gestational age (SGA) infants, not uncommonly associated with thrombocytopenia and leukopenia, corresponds very well with our own data.2 Their hypothesis for the pathogenesis behind the increased NRBC counts (chronic hypoxemia) is also in accordance with ours. Their discussion, however, seems to me rather descriptive. They do not comment on the low platelet and leukocyte counts, and do not offer any deeper explanation for possible mechanisms.
Intrauterine growth retardation is often caused by placental malfunction, leading to long-lasting intrauterine hypoxemia and stimulation of fetal erythropoiesis. This increases output of erythroblasts to the circulation, and is successively followed by polycythemia. Air breathing after birth brings the hypoxemic condition to an end. In our patients the erythroblasts disappeared from circulation during the first