What was going on when I was born?

Terrorists hurled grenades and fired submachine guns at crowds of holiday travelers at airports in Rome and Vienna today in attacks on check-in counters of El Al Israel Airlines. Authorities quoted by news services said the gunmen had killed at least 13 people, including 4 Americans, and wounded 113 in the two attacks. Four terrorists were killed, and three others were wounded and captured. While El Al appeared to be a target in both attacks, the authorities said the terrorists in Rome had also thrown grenades and fired indiscriminately with Soviet-made assault rifles into crowds of New York-bound passengers checking in at Pan American World Airways and Trans World Airlines. Terrorists Not Identified The assailants, who were not immediately identified, left the two airline terminals strewn with bloodied and torn bodies, luggage, overturned furniture and broken glass.

Although the Palestine Liberation Organization denied involvement in the attacks in Rome and Vienna, Israeli officials blamed the guerrilla group today and made it clear that Israel would respond at the appropriate time and place. ''Israel is shocked and outraged by these two new acts of senseless terror against innocent civilians,'' a Foreign Ministry statement said. ''The terrorist attacks come against a background of declarations by the head of the P.L.O., and those Arab states that support this organization, that these terrorists will cease terrorist operations outside of Israel. Israel will continue its struggle against terrorism in every place and at any time it sees fit.'' Syrian Missiles in Lebanon Meanwhile, Israeli analysts said Israel's ability to retaliate for the attacks had been limited by Syria's decision to move mobile surface-to-air missiles into Lebanon.

A section of the Brooklyn-Queens Expressway near the Williamsburg Bridge will be closed in January for reconstruction, and the work is expected to cause heavy traffic on the Brooklyn and Manhattan ends of the bridge for more than a year. The project, beginning in mid- to late January, is part of a five-year, $2.6 billion state program to rebuild many of the city's highways. The starting date depends on the availability of construction crews, according to the City Bureau of Traffic Operations. #70,000 Vehicles a Day Westbound traffic on the expressway, which the Traffic Bureau says is used by about 70,000 vehicles a day, will be rerouted at the Wythe Avenue exit in Brooklyn onto Williamsburg Street West for two and a half blocks. Cars will be able to get back on the expressway at the Flushing Avenue entrance.

Natasha Simpson, the 11-year-old daughter of a foreign correspondent in Rome, was on her way to New York with her family for a three-week vacation with friends and relatives. John Buonocore 3d, a 20-year-old student, was on his way home to Wilmington, Del., after a semester in Rome, just in time for his father's 50th birthday. Both died at Leonardo da Vinci Airport in Rome yesterday. They were among the 14 people killed there when terrorists hurled hand grenades and opened fire with submachine guns into crowds of holiday travelers. The Associated Press said two other Americans, Frederick Gage, of Madison, Wis., and Don Maland, of New Port Richey, Fla., were also killed.

The United States economy seems headed for a fourth consecutive year of expansion in 1986, but its course will be marred by gradually rising inflation and stubbornly high unemployment, according to a consensus of business and academic forecasters. The possibility of a recession, which at various times in the last year has seemed just over the horizon, has receded and is no longer regarded as an apparent threat. One important reason is the roaring bull market in stocks and bonds. By making investors richer, it has raised both confidence and the outlook for consumer spending, which accounts for two-thirds of the economy.

President Reagan and Mikhail S. Gorbachev have agreed to exchange videotaped New Year's Day greetings that are intended for broadcast in the United States and the Soviet Union, the White House announced today. The announcement said the exchanges would give Mr. Reagan his first chance to talk to the Soviet people directly on television and would give the Soviet leader the same chance to speak to the American people. The announcement came as Mr. Gorbachev, in Moscow, offered a cautiously upbeat assessment of relations between the Soviet Union and the United States, saying points of ''potential convergence'' had emerged in arms control talks. [Page 3.] Shortly before the announcement, Mr. Reagan, who flew here today to begin a weeklong vacation, issued his latest statement condemning the Soviet intervention in Afghanistan.

Finland has expanded its air defenses in the far north since a stray Soviet missile crashed there a year ago, a senior Foreign Ministry official said today.

Antonia Flores remembers the day her brother saw fire falling from the sky. It was nearly 20 years ago - Jan. 17, 1966, at 10:16 A.M., villagers say with precision - and Miss Flores was 6 years old. She was playing in a field when her brother looked up and screamed that pieces of fire were falling. The two frightened children made it as far as their backyard before stumbling among some cows. The pieces did not hit any people or houses - a miracle, the villagers say. Miss Flores remembers how, minutes later, she played curiously with a broken metal cylinder that had hit the ground.

Some 235 Polish tourists have failed to return to three ships docked at a West German port over the Christmas holidays, officials said today.

In what may be Africa's most expensive but least known emergency food program, airplanes of the International Committee of the Red Cross are flying about 400 tons of food weekly into Angola's fertile central highlands. The airlift is helping to feed 200,000 people who are suffering from malnutrition in an area that was once the breadbasket of Angola. It is not drought that has caused fields to lie fallow. Insterad, guerrillas of the Union for the Total Independence of Angola, led by Jonas Savimbi, have made it unsafe to cultivate the land or to transport crops to market.

Swazi villagers said today that South African troops crossed into the southeastern corner of the country this week and threatened to attack them if they gave shelter to guerrillas. Pretoria has recently repeated warnings to its black neighbors that it would ignore international boundaries to pursue attackers. A Swaziland police spokesman, Solly Mkhonta, said he was aware South African troops had crossed the border in the sparsely populated Lavumisa area, but he had no details.

The Nigerian Government today named 14 officers, including Gen. Mamman Vatsa, a member of the Armed Forces Ruling Council, who it said were behind an unsuccessful coup to overthrow President Ibrahim Babangida.