What was going on when I was born?

Surprising even their own trade group, American builders began work on new houses and apartments in February at an annual rate of 1.76 million units, the highest level since 1979, the Commerce Department reported today. The February figure, which was 2.9 percent above January's rate of housing starts, was the latest indication of the growing strength in the housing sector that is a major reason for the economic recovery now getting under way. Analysts attributed the strength to lower mortgage interest rates. Building Permits Up 1% The Commerce Department also said that building permits for future construction rose 1 percent in February from January's level, to an annual rate of 1.49 million, indicating that housing starts will remain strong in coming months. Both the housing starts rate and the permits rate were the highest since since September 1979. Permits had risen 13.3 percent in January.

THE open-plan bathroom, which made its first appearance at the beginning of the fitness craze several years ago, is on the way to becoming a basic amenity for some. Long hidden behind closed doors, the bathroom is now dropping its modesty and opening out into a spacious bath-dressing-exercise area. One of the newest versions of these multipurpose spaces is the pool-bathroom, with an extra-deep steeping tub or a large soaking area where the bather can enjoy comfort and contemplation. ''Bathrooms are becoming status rooms, a place in which people like to show off,'' said Estelle Ellis, president of Business Image, a marketing consultant in Manhattan. ''It is a way to let friends know that you are involved in health and body care.''

International The chief of the Soviet General Staff, Marshal Nikolai V. Ogarkov, suggested that if the American medium-range missiles planned for deployment in Europe were used against the Soviet Union, Moscow would retaliate directly against the United States. The marshal, in an interview, generally struck a moderate posture. He said that once nuclear war begins it cannot be limited and controlled. (Page A1, Column 5.) Five Salvadoran defendants were upheld by an Appellate Court judge. He ruled that the trial of five former National Guard members accused of the murder of four American churchwomen in 1980 could not proceed until a lower court provided more evidence in the case. (A6:1-3.)

JOHN V. FLEMING has a huge living room with a high ceiling but not much furniture - only a grand piano, two couches and a lamp. What take up the most space and make his living room different from all the others on University Place in Princeton, N.J., are the two old printing presses and five wooden cabinets filled with metal printer's type. Like Gutenberg and Benjamin Franklin, he is a printer. Like many latter-day lords of small presses, he prints for pleasure, not profit, on equipment that has been discarded by commercial print shops, sold at auctions and squeezed into homes. According to the American Amateur Printers' Association, there are between 10,000 and 100,000 amateur printers working out of living rooms, front halls, basements and garages around the nation. Les Boyer, the group's chairman, says a more precise estimate is difficult because some such hobbyists run off only an occasional poster or a handful of Christmas cards each winter, while others churn out multipage pamphlets or books on a more regular basis.

''The idea of nuclear war has never been tested. But by logic, to keep such a war limited will not be possible.

Most of the nation's major airlines yesterday came out in support of a plan by American Airlines to tie fares to the distance traveled. Trans World Airlines and Continental Air Lines said that they would apply the new fare structure to their entire route systems. This extends the markets that would be affected, because the two carriers fly some routes not served by American.

Measured by the wind-chill factor, the temperature was 86 degrees below zero, driving snow made it impossible to see more than a few feet, and even the ravens seemed to be huddling from the cold. It was a typical March day at Prudhoe Bay, America's biggest oilfield. ''It's like working on the moon,'' K.C. Kilty, a production technician, said of the effort required to maintain the mammoth oil wells, each of which pumps more than 400 times as much oil as the average well in the lower 48 states. The impact of the geological limitations is being magnified by falling oil prices. For Washington, each $1 drop in the world oil price means $547.5 million less in Alaskan ''windfall profits'' taxes each year.

House Republicans stalled action tonight on a nuclear freeze resolution after 13 hours of debate, as House Democrats failed on several efforts to speed consideration of the measure. More than 11 amendments were still pending when the House adjourned at 11:20 P.M. Democratic leaders considered many of those amendments dilatory and an effort to buy time for President Reagan to lobby members before the House again considers the measure next week. Some Democrats also opposed efforts to limit debate, on the ground that the issue deserved a full hearing on the House floor. Earlier in the night, the Democratic-controlled House narrowly rejected a Republican effort to significantly modify a resolution calling for a ''mutual and verifiable freeze and reductions in nuclear weapons'' between the United States and Soviet Union.

A Treasury official told Congress today that OPEC's 15 percent cut in oil prices could increase the output of goods and services in the United States by four-tenths of 1 percent and reduce consumer prices by nearly one percentage point. It was the Government's first estimate of the impact of the decision Monday by the Organization of Petroleum Exporting Countries to lower its basic price to $29 a barrel, from $34. The official, Charles Schotta, also said the department was assuming that the price would fall further, to $26 or $27. At that level, he said, the effects on the United States economy would be about one-third greater.

An article in Metropolitan Report Tuesday about May 3 school board elections in New York City incorrectly quoted Assemblyman Leonard P. Stavisky. He said that school board lines had not been revised since 1970 but had periodically been approved without change by the New York State Legislature.

Governor Cuomo and legislative leaders have agreed in principle to provide several hundred million dollars in new spending in the proposed state budget, according to several participants in the negotiations. But as talks continued through the day, there was no agreement between Democratic and Republican leaders on how to pay for the new spending, or exactly what programs would be restored. After a meeting that ended late tonight, the Senate majority leader, Warren M. Anderson, Repubican of Binghamton, said: ''I can see some movement. I think that by tomorrow night we will have something. We are not that far apart.''

Peter Martins, a principal dancer and choreographer of the New York City Ballet, has been put in charge of the company's daily operations, its board of directors announced yesterday. Mr. Martins will assume his responsibilities in association with Jerome Robbins, the choreographer who has a long worked with the company. Both men will hold the title of ballet master in chief. A spokesman for the company said Mr. Martins, who is 36 years old, would handle City Ballet's day-to-day artistic The future of the New York City Bal- let. News analysis, page C20. decision-making while Mr. Robbins, 64, whose ballets make up a large part of the City Ballet repertory, would continue in the advisory role he has held for many years.