Preeclampsia used to be called toxemia because it was thought to be caused by a toxin in a pregnant woman's bloodstream. This theory has been discarded, but researchers have yet to determine what causes preeclampsia. Possible causes may include:

  • Insufficient blood flow to the uterus
  • Damage to the blood vessels
  • A problem with the immune system
  • Poor diet

Other high blood pressure disorders during pregnancy

Preeclampsia is classified as one of four high blood pressure disorders that can occur during pregnancy. The other three are:

  • Gestational hypertension. Women with gestational hypertension have high blood pressure, but no excess protein in their urine. Some women with gestational hypertension eventually develop preeclampsia.
  • Chronic hypertension. Chronic hypertension is high blood pressure that appears before 20 weeks of pregnancy or lasts more than 12 weeks after delivery. Usually, chronic hypertension was present — but not detected — before pregnancy.
  • Preeclampsia superimposed on chronic hypertension. This condition occurs in women who have chronic high blood pressure before pregnancy who then develop worsening high blood pressure and protein in the urine during pregnancy.
Apr. 21, 2011