Eyeing a pile of baby clothes marked 25 percent off, a young woman turned to another shopper and lamented, "I wish the hell I knew whether I'm pregnant or not. I'd go hog wild and buy everything I need."

The bargains were hard to resist yesterday as the four Giant Department Stores began their going-out-of-business sales by knocking 25 percent off everything.

At the Tysons Corner store, where the potentially pregnant lady was shopping, the lines formed outside the door more than four hours before the 9 a.m. opening.

By midday, traffic was backed up for a half hour going in and out of the parking lots and the lines inside the store were worse.

At one time, the express checkout line - 5 items or less, no charges - contained 47 customers, give or take a few.

John Morlan of Falls Church said took the day off to buy camera gear. He said he was in line at 6 a.m., well behind a teenage CB-radio buyers who got there at 4:30.

By the time Morlan got to the camera department, the model he wanted was gone. Settling for a cheaper camera - marked down from $239 to $180 he threw in two lenses, a tripod and a few more accessories.

Only 45 minutes after the store opened, Morlan got to pay for his purchases. Behind him, still waiting to get into the camera department, were more than 100 shoppers, including one man who said he couldn't talk to a reporter because "I'm sick. That's what my boss thinks anyway."

Shopper John Denning, who had staked a claim on a color television set and wasn't about to desert it, complained that "you can't get anybody to write one up. I don't know what their system is, but it doesn't work."

The man in charge of Giant's Department Stores, vice president Robert Burke, said, however, that the system was working at least as well as could be expected.

"They're good people, they're good customers, they've always been good customers," said Burke, who was behind a counter in the Tysons Corner store rather than behind his desk at Giant's Lanham headquarters.

Giant officials estimate they have a $15 million inventory in the four department stores, which do about $45 million in business a year. That's too small to compete with Sears, Wards or K mart, Giant said, so it is closing the four stores to concentrate on its highly successful supermarket business and other operations.

Although the Tysons Corner store will close when the sale is completed sometime next month, its carpet department will be spun off as another Giant Carpet unit.

Burke said the four stores will be replenished with merchandise from Giant's warehouse, giving the camera and electronics departments, which were pretty well cleaned out yesterday, something to sell.

Giant turned down offers to sell merchandise to other dealers and plans to sell the stores down to the bare walls, he added.

Burke said that as the sale progresses, merchandise in the stores will be consolidated and prices marked down repeatedly to sell as much as possible.

The initial 25 per cent off was enough to satisfy most bargain hunters yesterday and many things didn't survive the first day's buying rush.

One woman eyed the last television set on a shelf, checked out the $88 price tag on the small black and white portable and said, "It's 25 per cent off that, I'll take it." She folded the antenna and got in line.

Dr. Daivd Foege of Alexandria was trundling a bigger color set out on its stand. The model was recommended by Consumer Reports, he said. "It's a good machine. It's regularly $399, it's $299 at George's and with 25 per cent off, it's $240 here," he said.

Admitting he'd probably have to wait for an hour to pay for it, Foege commented, "For $60 an hour, that's about what my time is worth."

"Yes, there are great bargains - if you can find them in this mad house," said Jean Anderson.

"It's an obstacle course," agreed her shopping companion. Betty Tederick.

"It's a shame they didn't have this before Christmas," said Anderson.

"This is the first time I've ever been to one of these things," she added, but Tederick recalled that the Tysons Corner Giant had been a Gem store once, and had gone out of business before when Gem folded.