High blood pressure and pre-eclampsia. Under normal circumstances the blood pressure drops during pregnancy as a result of the effects of the circulating hormones on the blood vessels, causing them to dilate and thereby reducing what is known as the total peripheral resistance. A ‘normal’ blood pressure at the start of pregnancy may be an indication that there is a risk of the development of pre-eclampsia, a condition where there pregnancy induced hypertension and the presence of protein in the urine (proteinuria) with or without associated oedema (swelling of the limbs and face). This is a dangerous condition which is caused by problems with placental blood flow. The blood pressure rises in order to try and compensate and there may be kidney and liver damage, together with the development of disseminated intravascular coagulation (described in the blood and circulation in the chest cavity section) and convulsions. It is more likely in women during their first pregnancy, in those with multiple pregnancies, and those who have a history of high blood pressure before becoming pregnant. The best way to manage pre-eclampsia is to make sure we monitor blood pressure and the urine for protein regularly, particularly after the 20th week of pregnancy, so the appropriate steps can be taken to prevent the development of eclampsia, which is the term used once convulsions have begun.