Blood Test May Curb Deaths of Fetuses : Medicine: Study links high levels of a protein with fatalities in the third trimester that occur despite a seemingly healthy pregnancy.

A simple blood test used to detect fetal abnormalities also can identify women in danger of losing a fetus late in a seemingly healthy pregnancy, according to a new study that raises the possibility of preventing some of the 29,000 fetal deaths that occur annually in the United States.

The study, based on data from California’s pioneering alpha-fetoprotein screening program, found that pregnant women with high levels of the protein in their blood faced 10 times the normal risk of having an apparently healthy fetus die in the third trimester.

“The implication of these findings is that it may be possible to prevent some of these pregnancy losses by careful surveillance and early delivery,” two researchers wrote in an editorial accompanying the study, published today in the New England Journal of Medicine.

Alpha-fetoprotein is produced in a fetus’s liver and gastrointestinal tract and can be found in the mother’s blood. Abnormal levels may indicate that the fetus has certain developmental problems, including brain and spinal cord defects and Down’s syndrome.

Because the test is used for screening, not diagnosis, women with abnormal levels are referred for additional forms of testing. In most cases, there are no problems with the pregnancy, but fetal abnormalities are found in a small number.

Researchers have long wondered what happens to those pregnancies in which no problems are found. Some studies have found a higher risk of a number of complications later on, including low birth weight and problems with the placenta.

In the new study, researchers at the California Department of Health Services, UC Berkeley and UC San Francisco compared the cases of 612 women whose pregnancies ended in fetal death with those of 2,501 women who gave birth to live infants.

The researchers relied on the records of the health department’s alpha-fetoprotein screening program, one of the largest such in the world. California is the only state in the country that requires all doctors to routinely offer women the screening.

The group found that women with the highest levels of the protein--three times the norm--were on the average 10.4 times more likely than others to have a fetus die. Women with twice the normal level were 2.4 times more likely to experience fetal death.

But the researchers noted that most of the fetal deaths they examined occurred in women with normal levels--in part because so many more women have normal levels. Although women with high levels were more likely than others to have a fetus die, most deaths were not associated with high levels.

“I think it’s an important development in terms of defining high-risk pregnancies, which is a serious problem in obstetrics,” said Dr. George Cunningham, chief of the health department’s genetic disease branch and an author of the paper.

“If we had a way to predict the group that was going to get into trouble . . . we could provide much more personal and inexpensive care to low-risk mothers and concentrate our high-powered technology and specialists on the high-risk mothers,” he said.

It is not yet clear, however, precisely how physicians might monitor apparently high-risk women. Available techniques include fetal heart-rate monitoring and sonography. But even the researchers acknowledged that it remains to be seen whether close monitoring will work.

“The $64 question that I can’t answer is will monitoring more often help,” said Dr. Mitchell S. Golbus, professor of obstetrics, gynecology and reproductive science at UC San Francisco and co-author of the paper. “Nobody knows that until (studies) are done.”

Another specialist in the field, Dr. Joe Leigh Simpson, a professor of obstetrics and gynecology at the University of Tennessee, said it also remains to be seen whether the test will identify risks that a careful obstetrician could not otherwise detect.

“If it’s only picking up people with a higher risk of (pregnancy-induced) hypertension . . . it is picking up what you would pick up in other ways,” Simpson said. “So that’s one of the crucial questions: Does it tell you anything other than what you already know?”