What was going on when I was born?

President Reagan said today that Republican women were making greater gains than Democratic women because they were ''doing it by merit'' without ''tokenism or cynical symbolism.'' Speaking at the White House to a group of Republican women active in politics, Mr. Reagan acknowledged that the selection of Representative Geraldine A. Ferraro as the Democratic Vice-Presidential nominee Excerpts from remarks, page 7. would be ''historic.'' The Congresswoman from Queens was the choice of Walter F. Mondale, the probable Democratic Presidential nominee. But Mr. Reagan challenged as ''foolishness'' the idea that her selection meant women were better served by the Democrats.

The instant public reaction to Representative Geraldine A. Ferraro as a Vice-Presidential candidate is mixed, with a wide range of minuses to accompany the pluses, according to a New York Times/CBS News Poll. The poll of 747 registered voters taken Thursday night, as Americans were first hearing of her selection as a running mate on the Democratic ticket by Walter F. Mondale, showed clearly negative reactions among the elderly, older and married men and Southerners. On the other hand, younger Americans, especially women, and undecided potential voters were positively affected by the choice. The poll thus illustrated how a surprise political move, which drew very little criticism and a great deal of praise from politicians Thursday, was evoking a different set of responses from people who were not professionally involved in the political process.

Jacek Kuron, left, Adam Michnik, two of four defendants, before military tribunal.

China announced Friday that its frontier guards repulsed a large-scale attack by Vietnam Thursday across their tense border after 10 hours of heavy combat. A dispatch by the official New China News Agency from what it said was the front line in Yunnan Province, where another battle was reported a month ago, said that after the fighting, ''the invaders fled in utter confusion.'' It said Chinese troops, working in the rain, had fortified their positions in preparation for a new attack. First Reported by Vietnam The border hostilities were confirmed by the Vietnamese News Agency. It accused China of shelling Ha Tuyen Province, which abuts Yunnan, with artillery and rockets since early July, killing civilians and seriously damaging property.

Nonmedical employees at 27 of New York City's private, nonprofit hospitals went on strike yesterday. Their union's leader described a two-year, 8 percent wage increase they were offered as ''insulting.'' The strike, by 46,000 workers, began with the change of the late-afternoon shifts, which varied at different hospitals. Picket lines had been set up at 6 A.M., but were withdrawn when negotiations continued on the union's demand for a two-year, 20 percent wage increase.

Despite expectations that the economy's stubbornly good health would aggravate inflation, an important measure of prices held steady in June for the third consecutive month, the Labor Department reported today. The department said its Producer Price Index for finished goods, reflecting the prices that industry charges retailers, showed no change in June and has risen only 2.2 percent over the past year. Another price index, for raw materials, fell last month by 1 percent, its third consecutive drop. In further indications of the economy's overall strength, the Government said industrial production rose five-tenths of 1 percent and retail sales eight-tenths of 1 percent, both exceeding their gains in May. (Page 45.)

Politicians in Queens are already competing for Mrs. Ferraro's House seat and a primary seems likely. Page 26. ELMORE, Minn., July 13 - In her first day of campaigning with Walter F. Mondale, Representative Geraldine A. Ferraro challenged Vice President Bush to two debates and discussed her positions on a range of issues, including abortion. Calling for Mr. Bush to debate her in the fall, Mrs. Ferraro said: ''Everyone keeps comparing me to Vice President Bush. That's delightful. I think we should have a debate or two.''

The publisher Robert Maxwell completed negotiations today to buy the Mirror Group of newspapers from Reed International Ltd. for $148 million. The Mirror Group comprises The Daily Mirror, one of Britain's largest circulation tabloids, as well as The Sunday Mirror, The Sunday People, The Sporting Life, The Scottish Daily Record and Sunday Mail, and a 5.8 percent share in Reuters. Mr. Maxwell has been trying for 15 years to buy a major national newspaper.

Prime Minister Margaret Thatcher has been thrown onto the defensive, a year after her re-election, by a series of serious economic and political problems. In the last two weeks her Government has had to contend with increases in bank and mortgage rates, a slumping pound and stock market, a worsening strike in the coal mines and a new strike on the docks, a sharp political reversal in the House of Lords, a crisis in Britain's relations with Nigeria and other difficulties. Her opponenents are said to sense a new vulnerability. The next general election is at least three years away, and so far Mrs. Thatcher's grip on the Conservative Party, which has an unassailable majority in the House of Commons, remains firm. There is no serious suggestion of a move to replace her as leader. But there is growing unrest among the backbench Tories, one of whom said this week that ''we haven't had any good news for a very long time indeed.''

At 1:30 A.M. on a Sunday, as they wait for the youths to begin spilling out after a Saturday night at the city's discoth eques, the groups of policemen strolling along Portland Street are hopeful, but they do not find talk of the economic recovery here in northwest England very convincing. ''We haven't seen it,'' a young policeman said. ''The discos used to draw crowds almost every night of the week. People cut way back during the recession, and they haven't really come back yet. Robberies are what is up.''

A 90-year-old ex-British army colonel said today that he would appeal a decision that upheld a baronetcy ruling in favor of his American cousin.

Lech Walesa, the Solidarity leader, was denied entry today to the court where four advisers to the labor movement went before a military tribunal on charges of having plotted to overthrow the Polish system by force. The trial was closed to Western journalists. But according to defense lawyers and a representative of the Polish press, the day involved a reading of the 30-page indictment and discussion of procedural matters. The session ended after six hours, with an adjournment until Wednesday when Jacek Kuron, who at 60 is the oldest of the defendants, will testify.