One in twenty women develop raised blood pressure, retention of fluid, and protein in their urine during the last three months of pregnancy. Without treatment this puzzling disease called pre-eclampsia can cause major problems for both mother and baby. Three years ago S Ananth Karumanchi, Assistant Professor of Medicine in Obstetrics and Gynecology at Harvard Medical School, showed that the blood of patients with pre-eclampsia has raised concentrations of a protein released from the placenta called sFlt1. The Harvard group believed that sFlt1 was key to the development of pre-eclampsia because, when it was injected into pregnant rats, it raised blood pressure and caused fluid retention with protein in the urine.

The small number of women who progress to a severe form of pre-eclampsia show a large and sudden increase in blood pressure that can lead to fits, liver damage and impaired blood clotting. All of these can affect the survival of both mother and baby. Karumanchi wondered whether another placental protein might be acting with sFlt1 to escalate the disease into the severe form. With eighteen colleagues from Boston and Toronto, Karumanchi  reported their research conclusions on-line in the June 4^th 2006 electronic publication of Nature Medicine.

Analysis of proteins extracted from placentas of women with pre-eclampsia showed increases in a protein called endoglin. This protein was discovered 20 years ago at the Hospital for Sick Children, Toronto by Michelle Letarte. Endoglin is a  blood vessel cell wall protein which is shed into the mother's circulation. The research workers discovered that the shed form, called soluble endoglin, was present in very high concentrations in the blood of women with the severe form of pre-eclampsia. When this protein was injected into pregnant rats it amplified the effects of sFlt1 and produced all the symptoms and signs of severe pre-eclampsia.

Severe pre-eclampsia is one of the world's major causes of death in mothers and babies. The discoveries by Karumanchi and his colleagues open the possibility of a lab test that will allow early diagnosis of pre-eclampsia and new treatments.