Usmagazine.com said Swift told Blender magazine last spring that she has never had sex.
"I read a very creative rumor this morning saying I'm pregnant, which is the most IMPOSSIBLE thing on the planet. Take my word for it. Impossible," the 18-year-old recording artist wrote on her MySpace page.
"This is absolutely not true. Taylor is not pregnant," the singer's publicist Paula Erickson subsequently told Usmagazine.com.
Swift and pop singer Joe Jonas, 19, dated for several months and broke up in October. Jonas wears a purity ring, signifying the vow he made to himself to remain a virgin until he weds.