Christina Aguilera is showing off her post-baby body for the first time since giving birth to her daughter with fiancé Matt Rutler, Summer Rain, in August.

Aguilera stepped out with Rutler on Sunday at the Breakthrough Prize Awards in Mountain View, California, where she wore a curve-hugging red dress with a plunging neckline.

The secret to Aguilera’s body is reportedly eating clean and a dedication to yoga.

"She is very dedicated to yoga. So much that she has never stopped practicing it. She did yoga the entire time she was pregnant," a source told E! News.

The source added that she’s been doing “private yoga sessions and loves how it makes her feel."

Aguilera gave birth to baby Summer via C-section less than three months ago. Summer is her first child with Rutler, whom she got engaged to this past Valentine's Day. She also has a 6-year-old son, Max, with her ex-husband Jordan Bratman.

Before getting pregnant with Summer, she slimmed down a lot after criticism over her weight.