What was going on when I was born?

Beginning a weeklong drive to win House and Senate approval of $14 million in aid for the Nicaraguan rebels, President Reagan warned Congress tonight that a vote against the aid would be ''literally a vote against peace.'' ''We cannot have the United States walk away from one of the greatest moral challenges in postwar history,'' Mr. Reagan said, asserting that failure to approve the aid would lead to ''more fighting, new wars and new bloodshed.'' Mr. Reagan's proposals drew criticism today from President Belisario Betancur of Colombia, who had said earlier this month that he viewed the President's plan positively. (Page A8.)

Governor Cuomo and former Senator Howard H. Baker Jr. of Tennessee will provide weekday radio commentaries for the Mutual Radio Network, the network announced today. Mr. Cuomo, a possible contender for the Democratic nomination for President, will do the commentary one day, and Mr. Baker, a possible contender for the Republican nomination, will do it the next.

Hospitals across the country are experiencing the steepest decline in use in at least 20 years, largely as a result of Federal cost containment policies that took effect last year, health officials and hospital administrators say. Admissions fell to about 35 million in 1984 from 36.3 million in 1983, a decline of 3.7 percent, according to the American Hospital Association.

Sales of new American-made automobiles fell by 6.6 percent in the first 10 days of April, the manufacturers reported today. Light truck sales were also off, the companies said, by 5 percent from the period last year. The changes are calculated on the basis of the daily selling rate, with nine selling days in the April 1-10 period this year and eight in 1984.

The river races here. Swollen with melted snows and spring rains, it rushes in a wild, white froth through still forests. Perched on the stern of a gray rubber raft, Ernie LaPrairie screamed ''power, power'' to eight paddle wielders. Instantly, eight yellow blades clawed the river, and the raft hurtled into the Cedar Ledges, a jumble of boulders lathered by waters pouring from the confluence of the Indian and Hudson Rivers.

An article in Science Times last Tuesday about children's sleep disorders misidentified two researchers. They are Dr. Marc Weissbluth of Chicago and Dr. Lawrence W. Brown, associate professor of pediatrics at the Medical College of Pennsylvania.

THERE are as many ways to become a schoolteacher in the United States as there are states, a fact that is leading some educators to advocate the use of a single examination that every teacher candidate in the country would have to pass. ''We believe very strongly that the benefits of reform will soon go down the drain in a teacher shortage and in lower standards to meet that shortage unless such an examination is created,'' said Albert Shanker, president of the American Federation of Teachers. ''We, for our part, are willing to do something that is very difficult for us, and that is to refuse to accept future teachers who do not meet that standard.''

The Wheeling-Pittsburgh Steel Corporation decided last night to file for protection under Chapter 11 of the Federal bankruptcy code after it failed to win concessions from its creditors, a United Steelworkers of America official said. The creditors are owed $514 million. Russell Gibbons, national communications director for the union, said in a telephone interview from Pittsburgh that the company told union officials at about 10 P.M. that the company's board had voted to seek bankruptcy protection. Wheeling-Pittsburgh planned a public announcement today, Mr. Gibbons said.

IN the psychological web that is marriage, there is no sure way to know which threads are crucial for

The South African Government said today that it had decided to abolish the laws forbidding marriage and sex across racial lines. Officials said they would accept a recommendation from a special committee of South Africa's new three-chamber Parliament to remove longstanding legal barriers to marriages and sexual relations between whites and and nonwhites.

Take Me Along,'' the revival of the musical adapted from Eugene O'Neill's ''Ah, Wilderness!'' with book by Joseph Stein and Robert Russell and music and lyrics by Bob Merrill, closed Sunday evening after one performance at the Martin Beck Theater. The play, directed by Thomas Gruenewald, ran for seven previews.

HUMAN genetic material, largely undamaged after 2,400 years, has been extracted from an Egyptian mummy and has been grown in the laboratory. The achievement is the most dramatic of a series of recent accomplishments using molecular biology to study links between modern and ancient life. Details of the recovery of DNA from the mummy will be published Thursday in the scientific journal Nature. The achievement by Dr. Svante Paabo of University of Uppsala in Sweden, is believed to be the first in which DNA, the genetic material in all forms of life, has been resurrected and duplicated from an ancient human or from any other specimen of such antiquity.