What was going on when I was born?

''It was very, very hard for me to leave the motherland, but I chose to be with my husband.'' - Helle Frejus, arriving in the United States from Moscow. [A9:1.]

Orders for American-made machine tools fell 19 percent in November from their October level, the National Machine Tool Builders' Association said in a report to be released today. The association said orders had declined 12.2 percent from November 1984.

When historians size up the major business strategies of 1985 they are likely to focus not only on the many billion-dollar mergers but also on several major court decisions that will help set rules for takeover battles in years to come. What is noteworthy about this year's key judicial decisions on takeovers, many legal experts say, is that they give corporate boards the go-ahead to use a larger arsenal of weapons to rebuff potential acquirers. A key one, for instance, was the ruling by Justice Joseph Walsh of the Delaware Supreme Court that upheld the Household International Corporation's ''poison pill'' strategy, which was aimed at making the company too expensive for an unwanted suitor. Another one, also in Delaware, gave the Unocal Corporation the green light to make a discriminatory tender offer that excluded a hostile bidder, T. Boone Pickens of the Mesa Petroleum Corporation. ''The trend of the Delaware decisions has been to give management greater power to resist takeovers,'' said Geoffrey P. Miller, a professor of corporations law at the University of Chicago.

Defense Minister Yitzhak Rabin said today that it was Israel's initial assessment that the shadowy, pro-Libyan Palestinian terrorist Abu Nidal was responsible for the Rome and Vienna airport attacks. ''I cannot say for sure,'' Mr. Rabin told a visiting American delegation, ''but that is our impression.'' In Rome the head of Italian military intelligence said that the four terrorists who killed 12 people there Friday were members of the Abu Nidal group and that they had been trained in Iran. The Ministry of Defense distanced itself from the official's remarks but diplomats in Rome and British and other Italian intelligence aides lent weight to the contention that Iran may have been involved. [Page A6.] Cabinet Considers Response The Israeli Cabinet today discussed how to respond to Friday's terrorist attacks, which left 18 people dead and more than 110 wounded.

Helle Frejus, the first of eight Soviet citizens to have been given permission by Moscow to live with their spouses in the United States, arrived at the Baltimore-Washington International Airport this afternoon. Mrs. Frejus left her home in Tallinn, the capital of Estonia, a Soviet Republic northwest of Moscow, Thursday morning. She flew to Baltimore today aboard a World Airways DC-10 en route to Los Angeles for a reunion with her 82-year-old husband, Kazimierz Frejus. Mrs. Frejus, who is 50 years old, is one of 10 people with American ties living in the Soviet Union who were told in November that they would get formal permission to live in the United States. The announcement that the 10 divided family cases - eight of them involving Soviet- and American-born spouses -would be resolved came just before the summit meeting between President Reagan and Mikhail S. Gorbachev, the Soviet leader, in Geneva in November.

Pedro Martinez rarely initiates a conversation and often covers his pale face with his hands, peering at the world from between his fingers. Still, the 4-year-old is making tentative progress at a twice-a-week play group at the Lower Eastside Service Center Recently he sang ''Fee, fie, fiddle-i-o'' with a bango-strumming music teacher and set up plastic soda bottles for a makeshift game of bowling. His parents are methadone patients at the center. ''He's improved in the talking,'' said Minerva Martinez, Pedro's mother, a heroin addict who agreed to enter methadone treatment last year after social workers threatened to place Pedro and his sister, who is 11, in foster care. ''Now he's driving me crazy with 'Mommy, school; Mommy, school.' He wants to come every day.''

The solution to one of the Statue of Liberty's last remaining mysteries, the source of its green copper skin, has been found at the end of a trail that led from Staten Island to a defunct copper mine on a Norwegian island in the North Sea. The discovery of the mine as the source for the copper had confounded history buffs for decades and capped 20 months of detective work that involved a pair of copper tweezers, Bell Laboratories scientists, a French mining company, scattered historical records and Norwegian Government officials, who now plan to make the mine into a museum. The finding is considered especially important because of the 100th anniversary dedication next July 4 of the statue, which is in the midst of a multimillion-dollar renovation. American officials, historians and others have been engaged in an effort to learn as much as possible about the distinctive national symbol, and virtually all of the other major details of the statue are known: the French workshop where it was made as a gift for the United States, the architect, the sculptor and the origin of other structural parts. 'A Missing Link' The details are to be included in official histories that are planned for the anniversary.

In 1962, a young venture capitalist named Robert L. Green bought a psychiatric hospital south of San Francisco, intending to use the site for an apartment complex. But after studying his acquisition, Mr. Green stuck with the hospital. It proved to be a good decision. Today, Mr. Green, an accountant by training, is chairman of Community Psychiatric Centers, which now owns 25 psychiatric hospitals in 12 states and Britain and has achieved a reputation as the most profitable psychiatric hospital chain in the nation. Since going public in 1969, Community has maintained annual earnings growth of 15 percent to 30 percent and has seen its stock soar. Now, however, deregulation is coming to the psychiatric hospital business, prompting pessimism among some analysts over whether Community will be able to maintain that level of growth in the face of new competition and pressures on cost. The company's stock, which reached a high in July of $35.75 on the New York Stock Exchange, closed Friday at $28.25.

Japanese business executives warned that they would curtail their investments in the United States if Congress ended the favorable tax treatment they have received. Saudi Arabians threatened to sell their United States securities rather than disclose how much they own. The political action committee of a Dutch-owned company contributed $726,000 to a campaign to defeat a proposed tax in California. As foreign investment has surged in the United States, such political activity by foreign corporations has escalated at all levels of government. Foreign business executives and their American lobbyists have become familiar figures in the corridors of Congress, state houses and city halls.

Mandatory retirement of most employees will be barred in New York State under a law that takes full effect on New Year's Day. The law, which will cover about 1.4 million public and private employees 70 years old and over, was passed last year after being recommended to the Legislature by Governor Cuomo. Public employees have been exempted from mandatory retirement under the law since last Jan. 1. New York will join 12 other states that prevent companies from forcing employees to retire at age 70, according to the National Conference of State Legislatures. In 1978, California became the first state to pass legislation specifically ending mandatory retirement. Federal law protects most employees from forced retirement until age 70.

What made the difference for the Giants against the San Francisco 49ers today was the New York pass rush up the middle that came chiefly from Jim Burt, Leonard Marshall and George Martin, the key defensive linemen. ''The pressure was there,'' said Joe Montana, the 49ers' quarterback, after San Francisco had lost the National Conference wild-card playoff game, 17-3. That was an acknowlegement and an understatement. Since the Montana era began for the 49ers in 1980, the team had beaten the Giants five consecutive times, twice in playoffs, with a cumulative score of 119-54. Montana had always made the big plays.

Concerned about the electronic payment systems that banks use to send money around the nation, the Federal Reserve Board is moving to introduce a sweeping change in how the systems are operated. The Fed has asked the banks to set limits voluntarily on how much they may overdraw their accounts at the Fed when using Fedwire, a system of computers and Telex connections operated by the central bank. Fedwire is the principal means by which banks exchange funds in transactions other than those involving checks. The self-determined limits on overdrafts, which have been criticized by Wall Street analysts, are due at the Fed tomorrow and are scheduled to take effect in March. Each bank's limit will also apply to the negative balances it builds up in other wire-transfer systems, such as the Clearing House Interbank Payments System, or Chips, the primary means by which banks exchange money internationally.