Factor VIII related antigen and coagulant activity in intrauterine growth retardation

Disseminated intravascular coagulation

Healthy pregnancy is accompanied by changes in the haemostatic system which convert it into a hypercoagulable state vulnerable to a spectrum of disorders ranging from venous thromboembolism to disseminated intravascular coagulation (DIC). This latter is always a secondary phenomenon triggered by specific disorders such as abruptio placentae and amniotic fluid embolism due to release of thromboplastin intravascularly or endothelial damage resulting from pre-eclampsia and sepsis. In modern obstetric practice the most common cause is haemorrhagic shock with delay in resuscitation leading to endothelial damage. The initial management of massive obstetric haemorrhage is the same whether associated with coagulopathy initially or not. Low-grade DIC, associated with pre-eclampsia, is monitored haematologically by serial platelet counts and serum fibrin degradation products (FDPs). Supportive measures and removal of the triggering mechanism are the key to successful management. Outcome depends primarily on our ability to deal with the trigger and not on direct attempts to correct the coagulation deficit.

Factor VIII in pregnancy and birthweight

Blood samples taken at 28 and 34 weeks of pregnancy from 495 women were assayed for factor VIII clotting activity (VIIIC) and factor VIII related antigen (VIIIR) to examine the distribution of these factors and to determine whether there was any relationship with birthweight. There was a small positive relationship of little clinical value between factor VIIIR and birthweight only when birthweight was adjusted for gestational age, sex of infant and parity. In pregnancies resulting in a male infant the level of factor VIIIC was lower at 34 weeks gestation than in pregnancies resulting in a female infant. A greater rise in the ratio of VIIIR/VIIIC was observed in women who had any type of hypertension when compared with normotensive pregnancies, but this was not associated with lower birthweight. Both factors VIIIR and VIIIC at 28 weeks gestation were lower for multiparous than for primiparous women, and were lower for those with eventual greater gestation at birth. Asian women had higher mean factor VIIIC than Caucasian women, a finding independent of the fact that women with blood group O had lower mean levels of factors VIIIR and VIIIC than women of other blood groups.

The factor VIII ratio in normal and pathological pregnancies

The factor VIII ratio was measured in 102 pregnant women (43 uncomplicated pregnancies, 19 with pre-eclampsia without fetal growth retardation, 8 pre-eclampsia complicated by fetal growth retardation, 12 with only fetal growth retardation and 20 with gestational diabetes). The pathological pregnancies showed a statistically significant elevation of the factor VIII ratio compared to the normal pregnancies. The group of pre-eclampsia complicated by fetal growth retardation showed the most marked increase of the factor VIII ratio. The results are discussed in relation to the hypothesis that the elevated factor VIII ratio is mainly due to the release of factor VIII antigen by various forms of vascular stress.

Factor VIII related antigen/coagulant activity ratio as a predictor of fetal growth retardation: a comparison with hormone and uric acid measurements

Factor VIII related antigen (VIIIRAg), Factor VIII coagulant activity (VIIIC), plasma uric acid, total plasma oestriol, plasma human placental lactogen (hPL) and urine oestrogen/creatinine ratio were measured in a group of 21 patients clinically suspected of fetal growth retardation and compared with normal pregnancy. Of the hormone assays, hPL was better than either oestrial or oestrogen/creatinine ratio at distinguishing between normal and growth retarded pregnancies. Uric acid levels tended to be higher than normal in patients with fetal growth retardation, but the best means of distinguishing normal from growth retarded pregnancies proved to be the VIIIRAg/VIIIC ratio. This ratio was significantly elevated in fetal growth retardation compared with normal pregnancy, and the increase was evident as early as 30 weeks gestation. Using the VIIIRAg/VIIIC ratio test, the outcome of 17 of the 21 suspect pregnancies could be correctly predicted.