Hemlines may be having their ups and downs this season, but many of the waistlines for spring have landed securely around the hips. And if the late fashion historian James Laver is right, that may be more significant than all the brouhaha about hemlines.

"During periods following great social upheavals," Laver once wrote, "women threw away their corsets, put their waists in the wrong place and cut off their hair." He cited the Empire period after the French Revolution, and the derriere emphasis that followed both world wars.

If Laver's theories apply to the low waistlines and short hair, the social significance has escaped the designers.

Geoffrey Beene says his waistlines are part of his obsession with everything Japanese.

Donna Karan at Anne Klein thinks dropped waistlines tightly wrapped with belts are like pretty girdles.

Gloria Sachs says the low-waistline look is a way to keep long hemlines from looking dowdy.

Whatever, the hip -- wrapped or belted or even bowed in some collections -- is becoming the focal point of fashion.

Beene has tied what look like candy-box ribbons -- obis or sashes -- low on the hip of many of his chemise dresses in what may have been the best collection of the season.

"Women look very sexy, very sensuous in loose clothes," said Beene after his show this week in New York. In an earlier collection, he had wrapped the hips in some designs to be worn at resorts this winter. But for spring his collection focuses clearly on the hips. "The dresses are often simple chemises that become very sexy once they are wrapped," he said. "They could be belted at the waistline or the hipline. The hips are simply sexier and newer."

Cora Ginsburg, a clothing collector and dealer in New York, has trouble with social theories drawn from fashion. "You can fit almost any theory to facts," she says. "But the fact is that clothes that are free and unfitted go with a lower waistline rather than a high one."

"Low waistbands are easier for women to wear," says Calvin Klein, who finds it more flattering. In fact, Klein admits to borrowing a shape of pants from his competitor Anne Klein. It is cut tight across the hips. "It makes women look slimmer."

"Hips are the essential focus because it is sexier," says Donna Karan, who with Louis Dell'Olio designs the Anne Klein collection. "These new belly wraps really hold you in and are comfortable. They carry you at a sensuous point where you move. Kind of like a pretty girdle." Some of her "girdles" are leather with belts tied over them to exaggerate the hip emphasis.

"Let's face it. Most women don't have waistlines. Something that skims over the body and is belted low is simply more flattering," says Gloria Sachs.

The slipping waistline is not just an American phenomenon this season. Paris and Milan designers who showed their spring collections last month are taking the same tack. "There is nothing more old-fashioned than styles with a top that is tucked into the waistline," said Giorgio Armani in Milan. Virtually all of his styles are developed from unfitted tops that are anchored at the hip with wrapped belts.

Bill Blass thinks the hip emphasis has spun off all the blouson styles that have caught on both here and in Europe. And while he likes a lot of his clothes belted that way, it doesn't bother him much that the style is not becoming to everyone and often not easy to wear.

"Let's face it," he says philosophically, "by the time women start wearing these clothes they will decide to tie them right at the [normal] waist."