Up to 8% of pregnant women develop pre-eclampsia (pregnancy-induced high blood pressure and presence of protein in the urine, which can lead to eclampsia, characterised by convulsions which can cause maternal and fetal death). Eclampsia is more common in less-developed countries, and accounts for around 50,000 maternal deaths a year worldwide. Maternal endothelial dysfunction (which prevents dilation of blood vessels resulting in increased blood pressure) is a feature of established pre-eclampsia, but whether this is a cause or consequence of the disorder is not clear.
Makrina Savvidou and colleagues from the Harris Birthright Centre, Kings College Hospital, London, UK, tested the hypothesis that endothelial dysfunction and raised blood concentrations of asymmetric dimethylarginine (ADMA), an agent which promotes endothelial dysfunction by the inhibition of nitric oxide, precede and contribute to the development of pre-eclampsia.
43 women studied during the second trimester of pregnancy had normal ultrasound examination of the uterine arteries and subsequently had a normal pregnancy outcome. A second group of 43 women had evidence of impaired placental blood flow; of these, 44% had normal outcome, 33% developed intrauterine growth restriction of the fetus, and 23% developed pre-eclampsia. Those who developed pre-eclampsia had reduced arterial dilation compared with women who had normal pregnancies. Increased ADMA was strongly associated with reduced arterial dilation, but only in the group of women who eventually developed pre-eclampsia.
Kypros Nicolaides, the senior investigator, comments: "Maternal endothelial function is impaired in women who eventually develop pre-eclampsia, and it occurs before the development of the clinical syndrome. Furthermore, women with high resistance placental circulation who are at risk of pre-eclampsia, intrauterine growth restriction, or both have raised concentrations of ADMA, which is a potential contributory factor for pre-eclampsia, and is responsible for endothelial dysfunction in some women. The results of this study may help the development of more accurate tests for the prediction and more effective treatment of pre-eclampsia."
Contact: Professor Kypros H Nicolaides, Harris Birthright Research Centre for Fetal Medicine, King's College Hospital, Denmark Hill, London SE5 8RX, UK;
T) 44-207-346-3040;
F) 44-207-738-3740;
E) kypros@fetalmedicine.com
Journal
The Lancet