FETAL FLOOD MONONUCLEAR CELL-DIVISION IN NORMAL AND PATHOLOGICAL PREGNANCIES

Fetal blood mononuclear cell division was measured using flow cytometr y in 53 normal pregnancies and 51 pathological pregnancies complicated either by anaemia due to red blood cell isoimmunisation (RCI: n = 21) , intrauterine growth retardation (SGA: n = 13) or abnormal karyotype (n = 17). In normal pregnancy, mononuclear cell division rates decreas ed with gestational age from a mean of 1.8% at 18 weeks to 1% at 40 we eks. Furthermore, there was a significant association between cell div ision and erythroblast count. The rates of cell division and erythrobl ast count were significantly increased in the chromosomally abnormal f etuses, and significantly decreased in the transfused RCI fetuses comp ared to the controls. Although the erythroblast count was elevated in the SGA fetuses, the mononuclear cell division was not significantly d ifferent from the controls. Fetal blood mononuclear cell division is e levated in early pregnancy and in chromosomally abnormal fetuses, prob ably as a consequence of increased numbers of circulating haemopoietic precursors. Mononuclear cell division is decreased in transfused RCI fetuses as a consequence of suppressed erythropoiesis. In SGA fetuses, despite the increased erythropoietic stimulation and erythroblastosis , cell division is not increased.