Some websites, including AwfulPlasticSurgery.com, are reporting that Britney Spears may have had her breast implants either removed or downsized. By the looks of recent photos this may very well be the case.
In my practice it is somewhat uncommon for women to considerably downsize their breast implants, but it does occur on occasion. Usually it's with older women who had large breast implants placed long ago and now don't want them so big anymore. Believe it or not, most women who have breast implants (at least the ones I put in) would get bigger than smaller!