There’s Lara Stone, in the Louis Vuitton ad by Steven Meisel, lying on her back in a woodsy setting with some birds. There’s Georgia May Jagger, photographed by Mario Testino forVersace, evidently at the moment she fell backward over a purple velvet chair and landed on a white fur blanket. There’s Jac Jagaciak, in a David Sims image for Calvin Klein, collapsed on a tree trunk. Fashion is having a recumbent moment, with models down all at once at Valentino, Miu Miu and Marc Jacobs, too.

“Sometimes things are in the air,” said Trey Laird, the advertising whiz behind campaigns for Donna Karan and Gap. “There are only so many ways you can show a handbag or jewelry or jeans. Composition-wise, sometimes people reach the same endpoint.”

The supine pose is not exactly new, Mr. Laird said, noting the Gucci jewelry ads with Drew Barrymore from 2007 and those spooky Lanvin ads last fall that showed Kristen McMenamy communing with some black cats on a couch. But it is unusual to see so many similarly posed images of women on their backs, back-to-back, in magazines.

“Not to mention Scott Brown,” said David Wolfe, the creative director of the Doneger Group, the trend forecasting company. Mr. Wolfe was referring to the 1982 Cosmopolitan centerfold images of the Republican politician that were widely circulated online during his Senate candidacy.

“It’s obviously sexual,” Mr. Wolfe said of the trend. “But the other thing I think of is animal psychology, because I do watch ‘The Dog Whisperer.’ When dogs or cats lower themselves to make themselves seem submissive, they are giving up their power and displaying their lack of aggression.”

Mr. Wolfe suggested that what we are seeing may be the modern equivalent of swooning. Given the dark tone of the times, it may reflect a desire (if only on the part of the fashion photographers) to return to traditional gender roles. Or it could just be that the spring fashions were so restrained that they didn’t know what else to do.

“It’s very hard to make a sexy picture of an elegant dress,” Mr. Wolfe said. “But throw the woman on the ground, and, oh, it’s a sexual come-on. That moves merchandise.”