The incidence of preeclampsia - the dangerous hypertensive disorder that occurs late in pregnancy - is increasing. While there are still more questions than answers about its causes, a number of recent research reports are beginning to shed some light on it.

Preeclampsia affects about 5% of all pregnancies but is responsible for 16% of maternal deaths. It is marked by hypertension, swelling of the hands, feet, and face, and the presence of protein in the urine. If not controlled, it can develop into eclampsia, which causes convulsions and coma and can be fatal.

Its causes are still unknown, but researchers from the University of Utah recently reported a genetic link in both the father and mother. Women whose mothers had preeclampsia were 3 times more likely to have it in their own pregnancies as others, and men whose mothers suffered from it were more than twice as likely to father a child whose birth was complicated by preeclampsia. These findings point to a genetic predisposition to the disorder.

Other experts have linked the increasing incidence to the fact that more women are delaying having their first child past the age of 35 and also to an increase in multiple births. In both of those situations, the risks for preeclampsia are higher than average. Other risk factors include having high blood pressure before pregnancy, a history of preeclampsia, and having diabetes, kidney disease, or certain blood clotting disorders.

The only cure for the condition is delivery, leading to many pre-term births. Now, however, there are reports from England that low doses of aspirin or other anti-clotting drugs reduced women's risks of developing the disorder, of a stillbirth or neonatal death, and of pre-term birth.

Another avenue of investigation is the antioxidant vitamins. One theory about the cause is that blood vessels, which are supposed to dilate early in pregnancy to allow increased blood flow, fail to do so in women who will develop preeclampsia. Blood flow is reduced to the baby and to her own organs, potentially causing kidney disease or other damage. This research will seek to determine whether vitamins could block oxygen damage to blood vessels that may contribute to preeclampsia. An NIH study of the potential for vitamins C and E to prevent or lessen its severity will soon get under way at Pittsburgh's Magee Women's Research Institute.

Sources:

• Esplin MS, Fausett MB, Fraser A et al. Paternal and maternal components of the predisposition to preeclampsia. New England Journal of Medicine (March) 2001;344:867-872. (Abs.)
• Pipkin FB. Risk factors for preeclampsia. New England Journal of Medicine (March) 2001;344:925-926.
• Duley L et al. British Medical Journal, Feb. 2001. (Reported in the Los Angeles Times, Feb. 12, 2001.)
• Neergard L. Pre-eclampsia is on the rise in the U.S. Los Angeles Times, March 19, 2001, p S3.