Preeclampsia is a condition that some women experience during pregnancy. Preeclampsia occurs after Week 20 of pregnancy and is characterized by an increase in blood pressure (hypertension) and high levels of protein in the urine (proteinuria). This condition used to be called toxemia of pregnancy.
Preeclampsia can also cause swelling, particularly in the face and hands. This swelling can lead to weight gain outside of the normal weight gain expected during pregnancy. It may also be accompanied by other symptoms such as blurred vision, headache, nausea, and pain in the upper abdomen.
About 3% to 7% of pregnancies are complicated by preeclampsia. Preeclampsia can be either mild or severe. If mild, 1 in 200 women with the disease go on to have full-blown eclampsia, a condition leading to seizures that can be fatal to both mother and fetus. But if preeclampsia is severe, as many as 1 in 60 may develop a seizure. Preeclampsia and eclampsia remain leading causes of maternal death in childbirth.
Women who have high blood pressure before pregnancy have a higher risk of miscarriage or giving birth to babies that are premature, underweight, or stillborn. Women who develop high blood pressure while pregnant (about 7% of pregnancies) run a slightly higher risk of these complications, and women with preeclampsia run the highest risk of all.
The causes of preeclampsia remain unknown. There are a few theories, and certain characteristics that are more common in sufferers. But the cause is not yet known.
We do know some risk factors. For example, preeclampsia tends to run in families, just like typical chronic high blood pressure. It's also more common in racial groups that are especially susceptible to high blood pressure, notably African Americans. This might suggest that people who are genetically susceptible to high blood pressure are more likely to develop preeclampsia.
The known risk factors for preeclampsia are:
- being over the age of 40, or under 20
- first pregnancy
- preeclampsia in previous pregnancies
- multiple fetuses (e.g., twins, triplets)
- African or Native American ancestry
- family history of preeclampsia
- preexisting high blood pressure, kidney disease, or blood disorders
- being overweight before pregnancy