Jennifer Lopez's publicist says that the star is "100 percent not pregnant," denying a rumor started by singer Jesse McCartney on an Atlanta radio station.

McCartney, telling Star 94 that his girlfriend, Katie Cassidy, is in the movie version of the TV show "Dallas," said that J-Lo was not canned, she left because of pregnancy.

A source described as "close to Jennifer" told US weekly that McCartney "doesn't even know Jennifer."

"His girlfriend has never even met Jennifer," the source said. "She just got cast in the movie after Jennifer was already out. Jennifer is shooting the cover of a high fashion magazine. Do you think she could wear couture if she was pregnant?"

Rumors that Lopez and husband Marc Anthony might soon be parents have been springing up on an almost monthly basis since their June 2004 wedding and Lopez has made no secret of her desire to reproduce.

In January 2006, word of Lopez's impending motherhood spread yet again after she and Anthony were spotting loading up on baby gear at various trendy Los Angeles infant stores. Once again, her rep spoke up to assure the world that once again, Lopez was not pregnant.

The gossip mill started up again in May 2006, when widely reported signs such as Lopez's fuller appearance in both her face and her belly and her gray roots were cited as evidence that she was indeed expecting. Yet again, her camp was ready with the denial.

That brings us up to the present, when both Lopez's abrupt departure from the Dallas project and McCartney's comment have fueled the flames of reproduction rumors only to be shut down yet again.

Stay tuned for next month's inevitable bumpwatch reports, be they true or false.