Pitting edema (unusual swelling, particularly of the hands, feet, or face, notable by leaving an indentation when pressed on) can be significant, and should be reported to a health care provider. In general, none of the signs of pre-eclampsia are specific, and even convulsions in pregnancy are more likely to have causes other than eclampsia in modern practice. Further, a symptom such as epigastric pain may be misinterpreted as heartburn. Common features of pre-eclampsia which are screened for during pre-natal visits include elevated blood pressure and excess protein in the urine. Diagnosis depends on finding a coincidence of several pre-eclamptic features, the final proof being their regression within the days and weeks after delivery. Causes
There is no definitive known cause of pre-eclampsia, though it is likely related to a number of factors. Some of these factors include:
Abnormal placentation (formation and development of the placenta)
Immunologic factors
Prior or existing maternal pathology—pre-eclampsia is seen more at a higher incidence in individuals with pre-existing hypertension, obesity, or antiphospholipid antibody syndrome or those with a history of pre-eclampsia
Dietary factors, e.g. calcium supplementation in areas where dietary calcium intake is low has been shown to reduce the risk of pre-eclampsia
Environmental factors, e.g.
air pollutionThose with long term high blood pressure have a risk 7 to 8 times higher than those without.Physiologically, research has linked pre-eclampsia to the following physiologic changes: alterations in the interaction between the maternal immune response and the placenta, placental injury, endothelial cell injury, altered vascular reactivity, oxidative stress, imbalance among vasoactive substances, decreased intravascular volume, and disseminated intravascular coagulation.While the exact cause of pre-eclampsia remains unclear, there is strong evidence that a major cause predisposing a susceptible woman to pre-eclampsia is an abnormally implanted placenta. This abnormally implanted placenta may result in poor uterine and placental perfusion, yielding a state of hypoxia and increased oxidative stress and the release of anti-angiogenic proteins along with inflammatory mediators into the maternal plasma. A major consequence of this sequence of events is generalized endothelial dysfunction. The abnormal implantation may stem from the maternal immune systems response to the placenta, specifically a lack of established immunological tolerance in pregnancy. Endothelial dysfunction results in hypertension and many of the other symptoms and complications associated with pre-eclampsia. Those with pre-eclampsia may have a lower risk of breast cancer.Abnormal chromosome 19 microRNA cluster (C19MC) impairs extravillus trophoblast cell invasion to the spiral arteries, causing high resistance, low blood flow, and low nutrient supply to the fetus. Genetic factors
Despite a lack of knowledge on specific causal mechanisms of pre-eclampsia, there is strong evidence to suggest it results from both environmental and heritable factors.