The Differences Between Mild and Severe Preeclampsia

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Preeclampsia is a pregnancy-related disorder that can be dangerous for both the pregnant woman and her unborn baby. The disorder is not very common, affecting about 5 to 8 percent of all pregnancies. However, it can progress rapidly, and lead to serious complications and even death for both a mother and her unborn baby. 

There is no treatment for preeclampsia: The only cure is delivery of the baby. Therefore, the more severe the condition is and the earlier it occurs in a pregnancy, the more difficult it is to manage. Balancing the needs of continued gestation for the baby and the risks the disease poses to both mother and baby is the challenge for women with the condition and their physician. 

The main features of preeclampsia are high blood pressure, protein in the urine and swelling of the extremities. Patients may notice sudden weight gain, headaches and changes in vision, but many women experience no symptoms at all. 

Mild vs. Severe Preeclampsia

Typically, preeclampsia is categorized by its severity, and distinguishing between mild and severe preeclampsia is important because the management strategies are very different.

Mild preeclampsia is diagnosed when:

  • Pregnancy is greater than 20 weeks
  • Blood pressure is greater than 140 systolic or 90 diastolic
  • 0.3g of protein is collected in a 24-hour urine sample or persistent 1+ protein measurement on urine dipstick
  • There are no other signs of problems with the mother or the baby

Severe preeclampsia is a more serious problem. Diagnosis of severe preeclampsia requires the basic features of mild preeclampsia as well as some indication of additional problems with either the mother or the baby. Thus, one of the following findings is also necessary for a diagnosis of severe preeclampsia:

  • Signs of central nervous system problems (a severe headache, blurry vision, altered mental status)
  • Signs of liver problems (nausea and/or vomiting with abdominal pain)
  • At least twice the normal measurements of certain liver enzymes on blood test
  • Very high blood pressure ( greater than 160 systolic or 110 diastolic)
  • Thrombocytopenia (low platelet count)
  • Greater than 5g of protein in a 24-hour sample
  • Very low urine output (less than 500mL in 24 hours)
  • Signs of respiratory problems (pulmonary edema, bluish tint to the skin)
  • Severe fetal growth restriction
  • Stroke

Other Blood Pressure Disorders During Pregnancy

Preeclampsia is one of numerous disorders related to high blood pressure during pregnancy, including:

  • Gestational hypertension, which features high blood pressure during pregnancy but not excess protein in their urine or signs of damage to other organs. However, some women with gestational hypertension will go on to develop preeclampsia.
  • Chronic hypertension, high blood pressure that was documented prior to pregnancy or that occurs before 20 weeks gestation. 
  • Chronic hypertension with superimposed preeclampsia, which is diagnosed in women who had chronic hypertension prior to pregnancy and then develop an exacerbation of their high blood pressure along with protein in the urine or other signs of preeclampsia during pregnancy.
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Article Sources

  • Diagnosis and Management of Preeclampsia and Eclampsia. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin #33, January 2002.