The District's infant mortality rate declined slightly in 1985, reversing a sharp increase in the rate the previous year, Mayor Marion Barry said yesterday at the kickoff of a public awareness campaign aimed at pregnant women in the metropolitan area.

"We have made infant mortality a high priority in the District of Columbia," Barry said at the Ritz Carlton Hotel, where officials of WRC-TV, Blue Cross and Blue Shield of the National Capital Area and the March of Dimes Birth Defects Foundation announced a $3 million program to lower the rates of infant deaths here.

The officials said the District has the highest infant mortality rates in the nation. U.S. rates are higher than in any other industrial nation and rank along with several Third World nations, they said.

The new statistics for the District show that in 1985 there were 204 deaths out of 9,840 live births, for a rate of 20.7 deaths per 1,000 births. The national infant mortality rate for the year was 10.6 per 1,000 births, according to provisional figures supplied by the National Institute on Health Statistics.

The city's rate in 1984 was 21.2 -- a 16.5 percent increase over the previous year's and a departure from the previous trend of declining rates.

The 18-month public awareness campaign, dubbed "Beautiful Babies: Right from the Start," will use television announcements, news programs and a documentary intended to educate expectant mothers about prenatal care. In addition, organizers plan to develop an incentive program that will give free medical and child care necessities to women who seek professional care.

"We are not going to say this campaign is a panacea, but certainly this is the best thing I have seen happen since I have been the mayor and living in Washington," said Barry, who presented campaign organizers with a $35,000 D.C. government check to fund the free services and goods for pregnant women.

The mayor, who last year said he would appoint a special assistant to coordinate efforts to reduce infant mortality, declined to discuss in detail his administration's current efforts in the area. He said he plans to provide details at a news conference today.

J. Herbert Niles, chairman of the mayor's advisory board on maternal and child health, said at the news conference that Barry administration officials had been planning a public awareness campaign and were gratified that the television station, Blue Cross and Blue Shield and the March of Dimes, were launching such a massive program.

"I must say this is beyond our wildest dreams that this project would come about," he said.

Niles added that the city is attempting to update its data collection system. The city, he said, hopes to computerize death certificate information in order to better analyze the underlying causes of infant mortality.

In a separate statement, Barry announced that the mortality rate among black infants in the District declined from 24.0 per 1,000 births to 22.9 in 1985 and the white infant mortality rate increased from 7.8 per 1,000 births to 10.6.