CHICAGO -- The excess risk that diabetic women have long run of having a baby with major birth defects -- a risk estimated at between 4 percent and 12 percent -- can be reduced to a normal level by intensively managing the pregnant woman's disease, researchers have found.

The finding is being published in today's Journal of the American Medical Association. It was based on a study of 194 diabetic women who became pregnant. In 84, intensive diabetes treatment began before pregnancy. Of the pregnancies, only one resulted in a child with a major birth defect. By contrast, of a control group consisting of the other 110 women who were six to 30 weeks pregnant before being given the same treatment, 12 children were born with problems.

The treatment consisted of training in how to perform daily blood sugar monitoring and to adjust their insulin doses accordingly. The women were also given individualized diet and exercise plans.

"Our data indicate it is necessary to begin education and management before conception to prevent major congenital anomalies in infants of diabetic mothers," the study said. The research was led by John L. Kitzmiller of the University of California at San Francisco medical school.

The researchers said typical congenital problems in children of diabetic mothers, such as heart defects, were formed in the first five to eight weeks of pregnancy.