After actress Cicely Tyson visited a maternity clinic in Chad this summer and saw both devastation and promise, she says she left "a totally different person."

"A mother had been in labor for 24 hours, terrified because she had had a stillborn baby the year before. She was afraid to release this child. She was perspiring and I had something so insignificant, a little packet of disposable towels . I wiped her brow and she smiled and said she liked the smell of the perfume. I was able to talk to her and explained if she didn't release the child we would not know whether it was alive or dead," recalled Tyson. The woman finally tried, and as the baby boy emerged, the physican discovered the umbilical cord was wrapped twice around the child's neck. "He would have died if she hadn't been in the hospital," said Tyson.

Tyson, who is best known for her portraits of women of great dignity who overcome obstacles, was in Washington yesterday to talk about her role as the chairperson of the 35th annual Halloween "Trick or Treat" campaign for UNICEF. She attended a UNICEF-sponsored lunch at WJLA-Channel 7. Later, she was honored at a reception by Rep. Mickey Leland (D-Tex.), chairman of the House Select Committee on Hunger, and businessman Abe Pollin, chairman of the Washington Advisory Council for UNICEF. Tomorrow, after a day in New York, she is scheduled to return to Washington to discuss relief projects with Nancy Reagan.

Her trip for UNICEF this summer, said the award-winning actress, "has given me an opportunity, and a consciousness which I thought I had. It has been enlarged. I came back a totally different person. It makes you look at yourself in relation to other human beings in the world."

Initially Tyson was "devastated" by what she saw in Africa. "You look at those children with the flesh just hanging on their bones, their eyes sunken to their heads, the distension of their stomachs -- oh God, the look on their faces of the agony of it all, the innocence of it all just ripped me. Then the hopelessness of their mothers . . . the best thing they could do was walk 30 miles to a clinic, to a food station, and the lines," said Tyson. She stopped talking and moved her chair back from the luncheon table and counted out the women lined up "for miles" for grain and water. The dining room carpet had become her desert and her long slender hands cups for food, and she said, "I never saw a mother take a mouthful."

"I came away with such hope primarily because I could see that the money was going to aid these people to aid themselves," said Tyson, who visited hospitals, water projects and schools in the Ivory Coast, Bourkina Fasso and Chad this summer. All the sites are funded by UNICEF. "You hear the cry -- send money -- and people ask 'Where is it going?' I needed to know. I was able to witness it. We cannot do enough, we cannot give enough. We are so fortunate."

In the past year, scores of Tyson's colleagues in the entertainment industry have raised money for African famine relief and for American farmers, as well as for research for AIDS (acquired immune deficiency syndrome).

"My head is just ringing," she says of the wave of the fund raising in Hollywood. "I am so proud to be a part of it. I had a visit with Carole Bayer Sager and Burt Bacharach the day before yesterday and they just wrote a song. Dionne Warwick, Stevie Wonder and Gladys Knight are singing and the title I think is 'What Are Friends For,' and the single, which will be released this week or next will go to AIDS research. We are in a position to do it. You have got to give back."

Tyson had been searching "for a place for myself to function in the midst of all this disaster. Then the phone rang one day." It was the appeal to work with UNICEF and her work has already extended beyond the year's commitment. She is helping to equip the clinic in Chad.

When the doctor monitored the baby's heartbeat, she used a primitive horn. When the baby was born, it was wrapped in cloth and put on a windowsill. Tyson is sending a stethoscope and blankets, linens, pillows.