Preeclampsia (formerly called toxemia of pregnancy) is a pregnancy-related condition that causes high blood pressure and affects the mother's kidneys, liver, brain, and placenta. Its cause is unknown.

Although preeclampsia usually develops after the 20th week of pregnancy, it can very rarely begin earlier. Preeclampsia can develop gradually or suddenly, and it may remain mild or become severe. If untreated, preeclampsia may damage the mother's liver or kidneys, deprive the fetus of oxygen, and cause eclampsia (seizures).

Signs of preeclampsia include:

• Elevated blood pressure (generally 140/90 mm Hg or higher). Any large increase in blood pressure should alert a woman and her doctor to possible risk.
• Persistent headache.
• Vision problems, such as blinking lights or blurry vision.
• Pain in the upper right abdomen.
• Lab results indicating elevated uric acid and/or protein in the urine (proteinuria).
• Swelling of the hands and face that does not go away during the day. This symptom of normal pregnancy may be a sign of preeclampsia if it is accompanied by other signs of preeclampsia.

A woman with any signs of preeclampsia is closely monitored by her doctor or midwife. Moderate preeclampsia is treated in the hospital with bed rest, magnesium sulfate, and sometimes medicine for high blood pressure. Delivery is the only true "cure" for preeclampsia.

When a woman has severe preeclampsia or is near term with mild to moderate preeclampsia, delivery is the best treatment. Labor may be started with medicine, unless a cesarean section is deemed necessary.

Within the first few days following delivery, the mother's blood pressure usually returns to normal; with severe preeclampsia, it may take several weeks for blood pressure to return to normal.