BRITNEY SPEARS’ mul­timillion-dollar career comeback was nearly de­railed by the pitter-patter of little feet!

The “Baby One More Time” sing­er has been showing some telltale signs of being preg­nant – and the timing couldn’t be worse. Having just signed a big bucks Las Ve­gas contract, Britney is on track to make one of the biggest comebacks the mu­sic industry has ever seen.

BUT “Britney was a nervous wreck be­cause she was afraid she was pregnant,” a source revealed.

“She was having waves of nausea, slight weight gain, drastic changes in her moods and intense cravings for certain foods.”

And the 31-year-old pop princess REALLY raised eyebrows earlier this month when she vomited aboard a helicopter that was transporting her to a promotional extravaganza in the Mojave Desert. The event was held to celebrate the two-year, $30 million contract she signed with Sin City’s Planet Hollywood.

The wave of nausea aboard the chopper is what pushed Brit to fi­nally take a pregnancy test – and it came up negative.

“Britney now thinks that her symptoms were just nervous energy about her up­coming show,” the source said.

Although mom-of-two Britney has expressed a desire to have a third child, she – along with her current flame, law-firm field researcher David Lucado, 27, and her dad/conserva­tor Jamie Spears – were said to be relieved that she’s not expecting.

“Britney definitely wants more kids,” the source added. “But Jamie knows it could destroy the come­back she’s worked so hard for.”