New research findings suggest a possible marker - and preventive treatment - for preeclampsia, the second leading cause of pre-term birth in the United States.
Researchers from Wake Forest University Baptist Medical Center (WFUBMC) in Winston-Salem, N.C., and the Pontificia University in Santiago, Chile, said levels of angiotensin-(1-7), a naturally occurring hormone that helps "brake" high blood pressure, increase during normal pregnancies and are low in pregnant women with preeclampsia. The findings were reported at a meeting of the American Heart Association''s Council for High Blood Pressure Research.
"While the cause of preeclampsia is currently unknown, this research indicates a possible mechanism for the condition," said David Merrill, M.D., a specialist in obstetrics and maternal/fetal medicine at WFUBMC. "Additional research is needed to show if low levels of angiotensin-(1-7) early in a pregnancy can predict preeclampsia, and if levels can be altered to prevent the disorder."
Preeclampsia, which affects about 5 percent of pregnancies, is characterized by high blood pressure, fluid retention and protein in the urine. In severe cases, untreated preeclampsia can lead to fetal or maternal death. Currently, the only treatment for preeclampsia is pre-term delivery.
K. Bridget Brosnihan, Ph.D., hypertension researcher at WFUBMC, said these were the first studies of the role of angiotensin-(1-7) in pregnancy. The hormone, identified earlier by WFUBMC researchers, causes blood vessels to dilate and is believed to be the body''s natural "braking system" against high blood pressure.
In one study, conducted by Brosnihan, Merrill and Michael Karoly, M.D., all of WFUMBC, researchers measured levels of angiotensin-(1-7) in blood samples from three groups of women. The hormone''s levels increased by 50 percent in normal pregnancies compared to a non-pregnant control group. In pregnant women with preeclampsia, levels of angiotensin-(1-7) were lower than in the pregnant subjects with normal blood pressure.
"These results confirm an increase in angiotensin-(1-7) in normal pregnancy and decreased levels in patients with preeclampsia," said Brosnihan.
In a separate study conducted by Gloria Valdes, M.D., at Pontificia University as well as Brosnihan and Carlos Ferrario, M.D., director of WFUBMC''s Hypertension and Vascular Disease Center, researchers looked at whether angiotensin-(1-7) levels could be measured from urine samples.
The results showed that in normal pregnancies, there was a progressive increase in angiotensin-(1-7) beginning at 12-13 weeks gestation and reaching a maximum level at 33-35 weeks. The peak levels were 13 times higher than in non-pregnant women.
"Preeclampsia is one of the major problems in obstetrics," said Merrill. "Understanding the mechanism - and whether these levels can serve as a marker - are the first step in developing preventive therapy."
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