When it comes to wedding fashion, perhaps nothing sets tongues atwitter faster than a visibly pregnant bride walking down the aisle in white.

Not ivory, cream, ecru or any other not-quite-white shade -- pure, blinding, blizzard white.

More maternity bridal designers appear to be offering that option this spring, and more pregnant brides-to-be seem to feel comfortable choosing it.

White has been the most popular color at MaternityBride.com since the online boutique opened three years ago, accounting for about half of all maternity wedding dress sales, said owner and designer Jessica Iverson.

It takes a strong woman to show up at her nuptials pregnant and wearing white. She's bound to face criticism from those who adhere to a tradition that deems it inappropriate.

Starting around the 1950s, white became the standard gown color in the United States for brides who had not been married before, did not have children and were not pregnant. White symbolized purity and virginity.

Although this Western notion persists, the history of white wedding gowns tells a different story.

They were worn in ancient Greece because white was a color of celebration.

In 1840, Queen Victoria of England raised eyebrows when she wore white for her marriage to Albert of Saxe-Coberg. White wedding gowns were uncommon at the time, and her choice was a sign of wealth rather than a proclamation of virginity or moral purity.

But somewhere along the way, as the white wedding dress became widely popular, it went from fashion statement to moral statement.

In the 50th anniversary edition of the "Amy Vanderbilt Complete Book of Etiquette," first published in 1952, authors Nancy Tuckerman and Nancy Dunnan wrote that a pregnant bride "must not ... walk up the aisle in a traditional wedding dress ... if her pregnancy will be very apparent. To do so is quite poor taste, considering her condition, and would probably be interpreted as an act of defiance or rebellion on her part. If the wedding is planned for so far in the future it's certain she'll be noticeably pregnant, she and her fiance can cancel their original plans in favor of a smaller, less formal wedding at an earlier date. She may still wear a long dress if she wants to, although a pale color would be more appropriate than all white."

This view is a reminder that there is still a stigma attached to the conception of children out of wedlock. It suggests that to show proper shame for such immoral behavior, a pregnant bride should don a colored dress to acknowledge her impurity and, while she's at it, have a low-key ceremony so it doesn't appear that she's flaunting her immorality. (Never mind that there's no equivalent public "sanction" for the father of the unborn child.)

The whole idea is fundamentally punitive and harkens back to the nation's Puritanical roots and an emphasis on personal piety and the appearance of moral rectitude.

But there's a problem with that sort of scarlet-letter judgmentalism: It doesn't honor the moral principle that supposedly undergirds the white-bridal-gown rule. If it did, then no woman who has had sex at any time before her wedding would be entitled to wear white.

And, given the lifestyle changes in the United States over the past several decades, white would probably be the least common gown color rather than the most popular. Currently, more than half of brides live with the groom prior to marriage, and a similar percentage are pregnant when they tie the knot, according to bridal industry surveys.

It was white-maternity-bridal-dress drama that caused Mrs. Iverson to start MaternityBride.com and to design white frocks as part of her collections. She was pregnant during her wedding in 2004 and had difficulty finding a white bridal gown that fit.

"People weren't helpful," she said. "It was a complete nightmare."

She ended up spending a lot of money altering a gown to make it fit over her growing belly and decided after her wedding to start Maternity Bride. One of her newest designs is a white pleated chiffon gown with detachable beaded straps and a sweep train.

Mrs. Iverson said relatives of some customers are uncomfortable with a white gown, but others are "entirely supportive and very untraditional."

Every now and then, she said, a bride will ask her: "Is it OK to wear white? My mom thought it was a little strange that I would want to wear white."

Her reply?

"This is your wedding day. You do whatever the heck you want."