Institute Activities and Advances
Studies conducted in recent years by researchers at the NICHD and elsewhere have found markers in the blood of pregnant women that seem to signal the later development of preeclampsia. Identifying such substances -related to the apparent biochemical basis for preeclampsia- is an important step in developing treatments for the condition as well as better ways to identify who is at risk.
Researchers at the NICHD's Division of Epidemiology, Statistics and Prevention Research (DESPR) found strong evidence that an imbalance of two proteins produced by the placenta is responsible for the symptoms of preeclampsia. Abnormally high levels of these proteins appear to deprive the blood vessels of substances needed to keep the lining of the blood vessels healthy. Deprived of these essential substances, the cells lining the blood vessels begin to sicken and die. As a result, blood pressure increases, and the blood vessels leach protein into the tissues and urine. Both proteins appear to contribute to the development of preeclampsia. Severe disease usually occurs in women with high levels of both measures and not in women with high levels of only one or the other. Other DESPR researchers are investigating the relationship of angiogenic factors to the pathogenesis of preeclampsia and their potential for identifying women at high risk of developing preeclampsia. Several studies are currently exploring this area of research.
Researchers in the NICHD's Pregnancy & Perinatology (PP) Branch also are investigating several avenues of research related to preeclampsia, including the impact of obesity on the condition, the potential role of autoimmunity, and fetal genetic contributions.
Although the exact mechanism of preeclampsia is unknown, the condition is widely believed to result from poor vascular development between the placenta and the uterus. In a normal pregnancy, trophoblastic cells, the main type of cell in the placenta, invade deep within the uterus and remodel small uterine arteries into large-diameter vessels. In preeclampsia, the trophoblastic cells fail to invade the uterus adequately, preventing the normal remodeling process of the uterine vessels. In turn, the poorly perfused placenta releases factors into the maternal circulation that result in the systemic symptoms of the disease.
PP Branch-supported research has helped determine the source and role of proteins that can prevent the growth of blood vessels in the placenta. Researchers also have documented an increase in these proteins under low oxygen conditions. Uric acid also has been investigated as a potential marker of preeclampsia.
In addition, researchers in the Program in Perinatal Research and Obstetrics, in the NICHD's Division of Intramural Research, are investigating preeclampsia as part of a larger effort to prevent preterm birth. Efforts have included examining the possibility that infection contributes to preeclampsia. Researchers also are calibrating measurements of growth factors in the blood and testing the reliability of these measurements as a way of predicting when women will develop preeclampsia. Their clinical findings indicate that this approach has promise for predicting when a woman will develop preeclampsia that requires delivery before the pregnancy reaches full term.
Other Activities and Advances
The PP Branch created the Maternal-Fetal Medicine Units Network in 1986 to focus on clinical questions in maternal-fetal medicine and obstetrics, particularly with respect to the continuing problem of preterm birth. Several studies affiliated with the network are investigating preeclampsia:
- The Combined Antioxidants and Preeclampsia Prediction Studies were designed to see if antioxidants (vitamins C and E) could prevent preeclampsia in women at low risk for the condition. The results showed that antioxidants do not decrease the incidence of preeclampsia nor reduce the risk of complications associated with pregnancy-related hypertension.1
- Two other studies assessed whether low-dose aspirin (60 mg) could lower the incidence of preeclampsia. One study found that low-dose aspirin did not reduce the incidence in women at high risk of the condition (those with diabetes, chronic hypertension, previous preeclampsia, or multifetal gestation).2 The other study found that low-dose aspirin marginally decreased the incidence of preeclampsia among women in their first pregnancy but increased the risk of placental abruption.3
- Combined Antioxidants and Preeclampsia Prediction Studies. (n.d.). Retrieved May 21, 2012, from http://www.bsc.gwu.edu/MFMU/Projects/capps.cgi [top]
- Randomized Clinical Trial of Low-Dose Aspirin to Prevent Preeclampsia in High Risk Women. (n.d.). Retrieved May 21, 2012, from http://www.bsc.gwu.edu/MFMU/Projects/lowdaspr.cgi [top]
- MFMU Network Randomized Clinical Trial of Low-Dose Aspirin as a Preventative of Preeclampsia. (n.d.). Retrieved May 21, 2012, from http://www.bsc.gwu.edu/MFMU/Projects/lowrisk.cgi [top]