When urine samples are collected over a 24-hour period, urine protein levels greater or equal to 300 milligrams indicate preeclampsia, according to Healthline.com. Two blood pressure readings taken six hours apart that are greater than 140/90 further indicate this diagnosis.
Preeclampsia is diagnosed after 20 weeks of pregnancy, Healthline.com states. Other signs that sometimes appear are swelling in the face or hands, headaches, vision problems and abdominal pain. Nausea, vomiting, low platelet count, and poor liver or kidney function also occur. Preeclampsia emerges in about 5 percent of pregnant women in developed countries. The condition is most common in pregnant women who have diabetes, are obese or are of advanced age.