Early results from blind AIDS tests among hospital patients show three in 1,000 infected with the virus that causes the deadly disease, according to a report released Thursday by federal health officials.

The national Centers for Disease Control, in one attempt to gauge the prevalence of infection with the virus that causes AIDS, has launched a program to test anonymously blood samples taken from hospital patients at 40 hospitals in 30 cities.So far, just four hospitals have been enrolled in the program, all in the Midwest. All patients are being tested except those who already have AIDS or related conditions.

In results from the four Midwestern hospitals, 0.3 percent of the 12,000 patients tested showed signs of infection by the acquired immune deficiency syndrome virus, the CDC said in a report Thursday.

Federal health officials continue to estimate that between 1 million and 1.5 million Americans from 0.4 percent to 0.6 percent are infected with AIDS virus. "No new data have become available to prompt a change of this estimate," the CDC said.

The Atlanta-based CDC stressed that it is in the earliest stages of the hospital study. "Accurate estimates of the prevalence . . . of (AIDS virus) infection in the entire U.S. population are not possible at this time," the agency said.

"These data are from just one region; they are not (necessarily) representative of the nation," said Dr. Tim Dondero, a CDC AIDS specialist. "You can't do a national estimate based on four spots."

The CDC expects to enroll all 40 hospitals in its testing program by September.

At the four hospitals reporting first, antibodies indicating infection by AIDS virus were more common among adults age 25 to 44. Rates also were higher for black and Hispanic persons than for whites, and higher for men than for women, the CDC said.

The CDC report also reviewed tests among prisoners and among childbearing women.

Out of 29,193 federal inmates tested by the U.S. Bureau of Prisons since last June, 843, or 2.9 percent, have tested positive for AIDS virus infection. That is little changed from a Justice Department announcement last fall, when 3 percent of the first inmates tested were positive.

The CDC said it hopes to contract with the National Institute of Justice and with a major university for AIDS testing of 10,000 inmates at 10 state prisons beginning this June.

In 52,326 tests of childbearing wom-en in the state of New York, researchers found an AIDS virus infection rate of 0.8 percent, the CDC said. In New York City, one woman in 61 showed antibodies against the AIDS virus, and 40 percent of those women passed the infections on to their newborn children, the CDC added.