Pre-eclampsia is a disorder of pregnancy characterized by the onset of high blood pressure and often a significant amount of protein in the urine. When it arises, the condition begins after 20 weeks of pregnancy. In severe cases of the disease there may be red blood cell breakdown, a low blood platelet count, impaired liver function, kidney dysfunction, swelling, shortness of breath due to fluid in the lungs, or visual disturbances. Pre-eclampsia increases the risk of undesirable outcomes for both the mother and the fetus. If left untreated, it may result in seizures at which point it is known as eclampsia.Risk factors for pre-eclampsia include obesity, prior hypertension, older age, and diabetes mellitus. It is also more frequent in a womans first pregnancy and if she is carrying twins. The underlying mechanism involves abnormal formation of blood vessels in the placenta amongst other factors. Most cases are diagnosed before delivery. Commonly, pre-eclampsia continues into the period after delivery, then known as postpartum pre-eclampsia. Rarely, pre-eclampsia may begin in the period after delivery. While historically both high blood pressure and protein in the urine were required to make the diagnosis, some definitions also include those with hypertension and any associated organ dysfunction. Blood pressure is defined as high when it is greater than 140 mmHg systolic or 90 mmHg diastolic at two separate times, more than four hours apart in a woman after twenty weeks of pregnancy.
Differential diagnosis
Pre-eclampsia can mimic and be confused with many other diseases, including chronic hypertension, chronic renal disease, primary seizure disorders, gallbladder and pancreatic disease, immune or thrombotic thrombocytopenic purpura, antiphospholipid syndrome and hemolytic-uremic syndrome. It must be considered a possibility in any pregnant woman beyond 20 weeks of gestation. It is particularly difficult to diagnose when pre-existing conditions such as hypertension are present. Women with acute fatty liver of pregnancy may also present with elevated blood pressure and protein in the urine, but differ by the extent of liver damage. Other disorders that can cause high blood pressure include thyrotoxicosis, pheochromocytoma, and drug misuse. Prevention
Preventive measures against pre-eclampsia have been heavily studied. Because the pathogenesis of pre-eclampsia is not completely understood, prevention remains a complex issue. Some currently accepted recommendations are:

Diet
Supplementation with a balanced protein and energy diet does not appear to reduce the risk of pre-eclampsia. Further, there is no evidence that changing salt intake has an effect.Supplementation with antioxidants such as vitamin C, D and E has no effect on pre-eclampsia incidence; therefore, supplementation with vitamins C, E, and D is not recommended for reducing the risk of pre-eclampsia.Calcium supplementation of at least 1 gram per day is recommended during pregnancy as it prevents pre-eclampsia where dietary calcium intake is low, especially for those at high risk. Higher selenium level is associated with lower incidence of pre-eclampsia. Higher cadmium level is associated with higher incidence of pre-eclampsia.