Aguilera threw up outside her limousine on the way to a romantic meal with Jordan Bratman at Toscana's Italian restaurant in Brentwood, Calif., reported the World Entertainment News Network.
That incident led to tabloid speculation that the star was expecting her first child.
An onlooker at the time said: "Christina looked really off color. She walked into the restaurant with her hand on her stomach and didn't look very happy at all."
A spokesperson later clarified, saying: "She has had stomach flu all week. She is not pregnant."