Thanks to internet message boards, a fairly small number of fetishists have been able to create rumors, anecdotes and reports that it is surprisingly popular for otherwise normal women to wear a disposable diaper as bridal lingerie. Going into an actual bridal boutique or asking people who really work in the wedding industry is more likely to elicit rolled eyes and sighs, as the legend is known by most professionals, albeit somewhat obscure.
The legend gained some independent validation when on an episode of CSI: Crime Scene Investigation in 2006 called "Rashomama" (itself a pun on Rashomon). In this episode the character of a wedding planner mentioned that because of the hectic and busy wedding day and bulky wedding dresses he sold "bridal diapers" for brides that couldn't find the time to go to the restroom and remove their dresses, then put their dresses back on. The characters on the show were surprised and wondering if the character was only kidding, which the show did not answer. As the show had already been known for episodes
Aside from internet forums and the one appearance on CSI there is virtually no evidence that "Bridal Diapers" are any kind of real wedding tradition, and the only brides that wear diapers on their wedding days are either 1. brides that are foolishly taken in by this urban legend, 2. diaper fetishists, 3. genuinely incontinent persons who wear diapers at other times and find nothing special in wearing a diaper under their wedding dress.