Physiological Changes During Pregnancy And Preeclampsia Studied By Magee-Womens Research Institute Scientists
TORONTO, June 3, 2002 — Every six minutes, a woman dies of a pregnancy complication called preeclampsia - nine women an hour, according to the Preeclampsia Foundation. Worldwide, the disorder, which is linked to hypertension, affects 3 million women a year, leading to an estimated 76,000 deaths - 30,000 in Africa alone.
"Research is closing in on this menace," said James M. Roberts, M.D., professor and chairman of research in the department of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh School of Medicine, director of Magee-Womens Research Institute and president of the International Society for the Study of Hypertension in Pregnancy. "But there still is much work to do."
Women who have previously experienced the condition, also known as toxemia and characterized by high blood pressure, swollen ankles and the presence of protein in the urine, have an even greater chance of developing the disorder in subsequent pregnancies. Other risk factors include maternal age of less than 25 or more than 35 years and preexisting hypertension, diabetes or kidney disease.
Scientists and physicians from across the globe are meeting here to learn from each other and present work on preeclampsia, which affects up to 7 percent of pregnancies and can have equally devastating consequences for infants.
"Preeclampsia is one of the leading causes of maternal, fetal and neonatal disability and death," explained Dr. Roberts.
The results of several clinical and basic science research studies will be presented by Magee-Womens Research Institute faculty at the 13th World Congress of the International Society for the Study of Hypertension in Pregnancy. Scientific sessions are scheduled June 2-5 at the Westin Harbour Castle Hotel.
Highlights of the findings include:
- Blood concentrations of a metabolic sugar called sialic acid are increased in women who develop preeclampsia with preterm delivery but not term delivery, Carl A. Hubel, Ph.D., assistant professor of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh School of Medicine, and his colleagues found. Preeclampsia that takes place in preterm is generally more severe than that which develops later, and is more likely to be associated with fetal growth restriction. Elevated levels of sialic acid indicate inflammation and are associated with an increased risk of atherosclerosis. Blood samples were studied from pregnant women who had experienced preeclampsia in a previous pregnancy. Women were randomized into two groups, receiving either 60 milligrams of aspirin, an anti-inflammatory drug, or a placebo daily. Early results also indicate that the low-dose aspirin may lessen this inflammatory response.
- Women who have had preeclampsia appear to be at greater risk for high blood pressure and cardiovascular disease later in life, Roberta Ness, M.D., M.P.H., associate professor of epidemiology and obstetrics, gynecology and reproductive sciences at the University of Pittsburgh School of Medicine, graduate student Patricia Agatisa and their colleagues found. By studying heart rate, blood pressure and forearm blood flow in pregnant women who had a prior preeclampsia, women with normal pregnancies, and never-pregnant women when under stress, investigators found that having had a normal pregnancy was associated with a positive long-term effect on blood vessel behavior that was not present in women who had previous preeclamptic pregnancies who had never been pregnant.
- While smoking during pregnancy has many adverse health effects on mother and fetus, it appears to decrease the risk of preeclampsia, Kristine Yoder Lain, M.D., assistant professor of obstetrics, gynecology and reproductive sciences at the University of Pittsburgh School of Medicine, and her colleagues found. Uric acid concentrations in the blood were compared between women with normal pregnancies, including smokers, nonsmokers and smokers who had quit smoking during pregnancy. Elevated levels of uric acid are observed during normal pregnancy among smokers. Higher uric acid levels also are observed in preeclampsia. Uric acid concentrations increased for all pregnant women, but the rate of increase was greatest among those who had quit smoking at the onset of pregnancy. Other blood studies of pregnant smokers found that certain cellular components associated with blood-vessel activation called fibronectin, vascular cellular adhesion molecule-1 and intracellular adhesion molecule-1 were either reduced or increased. Reasons for a decreased risk of preeclampsia among smokers remain elusive, researchers said.
- Women who experience preeclampsia early in pregnancy have a greater chance of delivering preterm, lower birth-weight babies in a subsequent pregnancy even if they do not develop preeclampsia then, Dr. Lain, M.D., and her colleagues found. Because one theoretical cause of preeclampsia is abnormal implantation, outcomes for subsequent non-preeclamptic pregnancies were compared among women who had preeclampsia early or late in a previous pregnancy, as well as among women who did not develop the disorder. Researchers found that women who experienced preeclampsia early in pregnancy tended to deliver smaller infants, and to deliver them earlier in subsequent pregnancies even though they did not develop preeclampsia again. Results may indicate that abnormal implantation persists even in the absence of clinical preeclampsia.
- Even a mild deficiency in vitamin C appears to negatively affect vascular elasticity and function, Dr. Hubel, and his colleagues found. By comparing arterial pressure and elasticity in pregnant and non-pregnant rats that, like humans, are unable to synthesize vitamin C, the scientists learned that vessel stiffness increased in pregnant rats when vitamin C concentrations were restricted. Non-pregnant rats were not similarly affected by vitamin C restriction, however. These results were observed in spite of a natural physiologic change initiated by pregnancy that typically increases blood vessel elasticity, which in turn affects blood pressure. While researchers have long known that vitamin C concentrations are decreased in women with preeclampsia, the specific effect on vascular function remains unclear.
Members of the International Society for the Study of Hypertension in Pregnancy meet formally every two years to exchange ideas and foster collaboration. Membership includes physicians and researchers in the fields of obstetrics, gynecology, epidemiology and other public health specialties.
Magee-Womens Research Institute, the country's first institute devoted to women and infants, was formed in 1992 by Magee-Womens Hospital of the University of Pittsburgh Medical Center.
The University of Pittsburgh School of Medicine's department of obstetrics, gynecology and reproductive sciences is one of the top three funded departments by the National Institutes of Health.