Eclampsia, like pre-eclampsia, tends to occur more commonly in first pregnancies and young mothers where it is thought that novel exposure to paternal antigens is involved. Furthermore, women with pre-existing vascular diseases (hypertension, diabetes, and nephropathy) or thrombophilic diseases such as the antiphospholipid syndrome are at higher risk to develop pre-eclampsia and eclampsia. Having a large placenta (multiple gestation, hydatidiform mole) also predisposes women to eclampsia. In addition, there is a genetic component: a woman whose mother or sister had the condition is at higher risk than otherwise.[15] Women who have experienced eclampsia are at increased risk for pre-eclampsia/eclampsia in a later pregnancy. Pulmonary edema is a rather common complication of severe eclampsia affecting approximately 3% of the people with eclampsia: most is caused by too much intravenous fluid.