Levels of HLA-G, a molecule secreted by the placenta that serves as a sort of "fetal protection system," were significantly lower as early as the first trimester in women who subsequently developed preeclampsia, according to research published in the American Journal of Obstetrics and Gynecology.

Drs. Clifford Librach and Shang-mian Yie of the Department of Obstetrics and Gynecology at Sunnybrook & Women’s, in collaboration with Dr. Robert Taylor of the University of California, San Francisco, monitored 12 women who later developed pre-eclampsia and compared them to 12 matched control patients during the first, second and third trimesters.

Closer Monitoring

"If we can find out about the women at risk very early on, we can monitor the mother and baby more closely and allow early detection of this condition," says Dr. Clifford Librach.

"This might mean delivering the baby earlier to avoid the onset of severe pre-eclampsia and potential serious complications for the mother and baby," he explains. "This test will also allow us to study woman at high risk for pre-eclampsia and test potential therapies for prevention of this disease."

Complications for the baby may include growth retardation, fetal distress and stillbirth. The mother may suffer high blood pressure, seizures, stroke, bleeding disorders and liver disease.

Prematurity resulting from pre-eclampsia can result in further complications for the baby, including blindness, cerebral palsy and mental retardation.

Cloaking Molecule

"There is much evidence from our investigation, and from other researchers, to show that HLA-G may have an important role in protection of the baby from the mother’s immune system during pregnancy, by acting as a sort of 'universally accepted identity card,'" says Dr. Librach.

"This molecule acts like a cloaking or disguising molecule in the placenta so that the baby, who also inherits paternal genes, doesn't look foreign to the mother's immune system," he points out. "Lower levels of this molecule may impair this natural protective mechanism and, over time, somehow result in this disease."

HLA-G is the first marker that shows promise to be a predictor of pre-eclampsia as early as the first trimester, Dr. Librach notes.

"More studies on larger numbers of pregnant women need to be done to determine if this test can be used on a routine basis," he suggests.