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This article waslast modified on 10 July 2017.
Pre-eclampsia is the development of increased blood pressure and protein in the urine during pregnancy, usually after the 32nd week. There are often no symptoms except those due to mild fluid retention. The condition develops in about 4% of first pregnancies but is less common in later pregnancies. There is poor development of the placenta, the growth of the baby is slowed and delivery may be premature. Those affected need to be monitored closely because about one in 50 will develop full eclampsia in the last three months of pregnancy or during labour. Eclampsia brings fits, fluid in the lungs, kidney failure and clotting problems and is a life-threatening condition for both mother and child.

The cause of pre-eclampsia is unknown, though there is research evidence to support the general idea that a poor blood supply to the placenta causes it to release molecules into the mother's circulation that affect her blood vessels. Among the many substances that have been investigated is the Vascular Endothelial Growth Factor (VEGF) family of molecules which includes some that regulate the function of the lining of blood vessels (the endothelium), the leakiness of blood vessel walls, blood flow and the stimulation of new blood vessel formation.

In 2002 David Bates and co-workers from the Microvascular Research Laboratories in the University of Bristol were the first to identify VEGF165b, a protein of 165 amino acids that inhibits the growth of new blood vessels. A study of VEGF165b during the course of pregnancy was published online by David Bates with a clinical and scientific team from the University of Bristol in the journal Clinical Science on 1 October 2008.

The molecule was measured using an enzyme-linked immunoassay (ELISA) in blood plasma from women who were not pregnant, from women who maintained a normal blood pressure throughout pregnancy and from women who later developed pre-eclampsia. At 12 weeks the VEGF165b concentrations in those with normal blood pressures were 10 times higher than the values in non-pregnant women. In contrast, the values in those who later developed pre-eclampsia did not differ from non-pregnant values. At the time of birth (term) the values in the two groups of pregnant women were both higher than in non-pregnant women and were similar. Thus, the elevation of VEGF165b concentrations in pregnancy is delayed in those who later develop pre-eclampsia. The researchers concluded that low plasma VEGF165b may prove to be a clinically useful marker in the first three months of pregnancy for an increased risk of developing pre-eclampsia.

This study was funded by the British Heart Foundation. Its Associate Medical Director, Professor Jeremy Pearson, said 'These researchers have made a vital finding that, if confirmed by other studies, has the potential to translate into a simple test that could save many lives.'