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What is Preeclampsia?


Updated June 19, 2014

Question: What is Preeclampsia?
Answer: Preeclampsia is a pregnancy-related condition that includes elevated blood pressure. Specifically, it is the new onset of high blood pressure and proteinuria (protein in the urine) in a pregnant woman who is beyond 20 weeks gestation. This is an important distinction, since women who had high blood pressure before becoming pregnant may sometimes look like they have preeclampsia, but should be treated according to a different set of clinical guidelines.

A preeclampsia diagnosis depends on clearly established rules. A diagnosis of preeclampsia requires:

  • Onset of high blood pressure after 20 weeks gestation with a systolic blood pressure of >140mmHg or diastolic blood pressure >90mmHg
  • Protein in the urine

More than one blood pressure reading must be taken to diagnose preeclampsia. Guidelines say that the measurements must be at least six hours apart, though they are usually taken on successive days (though they can't be be longer than seven days apart).

Along with high blood pressure, protein in the urine is the other major finding needed to make a diagnosis of preeclampsia. Urine must be collected and analyzed for the presence of protein. This can be done either by collecting and analyzing all urine produced in 24 hours, or by analyzing a single urine sample. The amount of protein required for diagnosis in each sample is:

  • 0.3g total in a 24-hour sample
  • 30mg/dL or +1 on a single sample
Learn More About Preeclampsia:
What is Preeclampsia?
What are the Symptoms of Preeclampsia?
Are there Different Kinds of Preeclampsia?
Is Preeclampsia Dangerous?
How is Preeclampsia Treated?


Cunningham, FG., Lindheimer, MD. Hypertension in Pregnancy. New England Journal of Medicine, 326(14):927-32.

Working group report on high blood pressure in pregnancy. National Institutes of Health, Washington, DC 2000.

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