Credit: Jason Merritt/Getty Images

For Natalie Portman, staying fit while pregnant is going just swimmingly.

"I have been swimming every day," the 29-year-old engaged mom-to-be told of her pregnancy workout routine backstage at Sunday's Golden Globes.

Now through her first trimester, the Best Actress winner says she's trying to keep calm as she preps for motherhood.

"When I am in my womb-like environment, I am hoping the baby is feeling peaceful," she said.

Still, the vegan actress -- who dropped an astonishing 20 lbs. while training for her Black Swan role -- realizes that eating for two does have its benefits.

"I told [director] Darren Aronofsky, I was like, 'First you got me skinny, and now you're getting my fat,' because he introduced me to my fiance," she told Extra at the Palm Springs International Film Festival. "It's the greatest gift he ever gave me."

At Sunday's Globes, Portman was in a jokey yet sentimental mood when it came to her Black Swan choreographer fiance, Benjamin Millepied.

"Thank you to Benjamin, who is helping me continue this creation of creating more life," Portman said during her acceptance speech.

Portman later noted that Millepied, 33, had a small role in the film, playing a ballet-dancer character who said he "wouldn't sleep" with Portman's ballerina.

"It's not true!" Portman bellowed, laughing. "He totally wants to sleep with me!"