Haemoconcentration in severe pre-eclampsia.

The last maternal haemoglobin (Hb) concentration before delivery was related to the perinatal outcome in 87 non-anaemic women suffering from severe pre-eclampsia. Abnormally high Hb concentrations were found in most women with evidence of placental dysfunction. An inverse correlation was found between the centile weight of the newborn and the maternal Hb. Significantly higher Hb levels were found in pregnancies complicated by fetal growth retardation and perinatal distress compared with those in pregnancies with good outcomes. Particularly high levels were found in pregnancies that ended in perinatal deaths. The hypothesis is put forward that raised haemoconcentration during severe pre-eclampsia causes increased blood viscosity which predisposes to placental pathology and initiates a vicious circle.