In a recent study of pregnant baboons–primates whose hormones during pregnancy act much like those of humans–low estrogen levels caused more than half to miscarry. Ultrasound monitoring revealed that the fetuses died before the miscarriages.
Eugene D. Albrecht, PhD, professor of obstetrics, gynecology and reproductive sciences at the University of Maryland School of Medicine, presented results of the study at a March 14 symposium on "Fetal Signaling and Labor," at the Society for Gynecological Investigation’s 45th annual meeting in Atlanta.
"Our findings indicate that estrogen plays a critically important physiological role in the maintenance of pregnancy and in fetal viability," Albrecht says.
Albrecht and his collaborator, Gerald J. Pepe, PhD, professor of physiology at Eastern Virginia Medical School, artificially suppressed estrogen levels in 22 pregnant baboons. Seven also received an estrogen supplement that restored levels of the hormone to that of normal pregnancy. Another 20 baboons were left untreated, as controls.
Pregnancy proceeded normally to term in 95 percent of the controls, but only 45 percent of the animals whose estrogen formation was suppressed were able to maintain their pregnancies, Albrecht reports. The other 55 percent miscarried. Monitoring six of the estrogen-suppressed baboons with ultrasound, the researchers found no fetal heartbeat, indicating that the fetuses had died before the miscarriages, he says.
In contrast, all of the animals treated with both an estrogen suppressant and an estrogen supplement maintained their pregnancies, the perinatal endocrinologist adds.
Estrogen’s role in maintaining pregnancy has long been debated. Some scientists point out that women with a mutation in their estrogen receptor have a 50 percent miscarriage rate, indicating the importance of estrogen. Others say the fact that pregnancy has been maintained in women whose estrogen levels were low proves that the hormone plays no essential role in the physiology of pregnancy. Albrecht and Pepe, who have been working for more than two decades to piece together the estrogen-in-pregnancy puzzle, previously showed that estrogen plays at least two vital roles in what they call "the fetal-placental dialogue that goes on during primate pregnancy:" It regulates the production of another essential hormone, progesterone, and promotes normal development, maturation and function of the placenta and fetal adrenal glands. A fetus’s adrenal glands produce cortisol, a steroid hormone that is critical to maturation of the lungs, liver, and other developing organs and tissues.
Their research was funded by the National Institute of Child Health and Human Development of the National Institutes of Health.
The University of Maryland trains approximately 56 percent of the state's doctors, lawyers, pharmacists and social workers and the majority of its dentists. In addition, nearly 90 percent of the graduates of the School of Nursing work in Maryland.
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