FACTOR-VIII RELATED ANTIGEN AND COAGULANT ACTIVITY IN INTRA-UTERINE GROWTH-RETARDATION

Normal ranges of haemostatic values were determined by studying sixteen normal pregnant women sequentially from 28 weeks to term. Twenty-one patients clinically suspected of intra-uterine growth retardation (I.U.G.R.) were also studied: at delivery, nine of these pregnancies resulted in a baby below the 10th percentile of weight for gestational age (confirmed I.U.G.R. group), while the remaining twelve were above the 10th percentile (non-confirmed I.U.G.R. group). In normal pregnancies between 28 and 38 weeks' gestation, the ratio of factor VIII related antigen (VIII RAg) to factor VIII coagulant activity (VIII C) ranged from 0.50 to 1.90 (mean 1.20). In 17 of the 21 suspect pregnancies this ratio correctly discriminated between the confirmed and non-confirmed I.U.G.R. groups, VIII RAg/VIII C being markedly raised in 6 of the confirmed I.U.G.R. group and normal in 11 of the non-confirmed I.U.G.R. group. There were three false negative results and one result too near the borderline to be interpreted. In contrast, platelet counts, fibrinogen levels, soluble fibrin complexes and fibrin/fibrinogen degradation products did not discriminate between the confirmed and non-confirmed I.U.G.R. groups. The VIII RAg/VIII C ratio is the best haemostatic test for predicting small-fordates babies. © 1979.