What it is. High blood pressure and protein in the urine that afflicts up to 8 percent of pregnant women. It can cause blood clotting and impaired kidney and liver function.
What causes it. One study suggests preeclampsia may be caused by a protein that halts the growth of blood vessels in the placenta, while another study suggests the odds for it increase with a woman's prepregnancy body-mass index. At highest risk: moms carrying more than one fetus, women over 40, or those who have a close relative who's had preeclampsia.
Symptoms. High blood pressure, swelling in the hands and feet, severe headaches, blood in the urine, or extreme nausea.
Can you prevent it? You can decrease the likelihood by staying at a healthy weight, eating a nutritious diet, and getting regular exercise.