Pregnant Rumer Willis Shows Growing Baby Bump in Black and White Athleisure Look

Rumer Willis leaving a workout class, carrying her new Warmies while showing off her baby bump wearing sustainable brand Losano
Rumer Willis leaving a workout class, carrying her new Warmies while showing off her baby bump wearing sustainable brand Losano
  • Oops!
    Something went wrong.
    Please try again later.
  • Oops!
    Something went wrong.
    Please try again later.
  • Oops!
    Something went wrong.
    Please try again later.

Michael Simon/Shutterstock

Rumer Willis is in mom-on-the-go mode as she prepares for her first baby.

The Once Upon a Time in Hollywood actress, 34, showcased her growing baby bump as she stepped out Monday to run errands in a black and white two-piece Losano activewear set.

The star, who announced her pregnancy last month with boyfriend Derek Richard Thomas, paired the brand's Showstopper Sculpted Bra with the Criss-Cross Pocket Legging, layering the look with an open button-down black shirt, while carrying a Warmies stuffed dog.

Rumer Willis leaving a workout class, carrying her new Warmies while showing off her baby bump wearing sustainable brand Losano
Rumer Willis leaving a workout class, carrying her new Warmies while showing off her baby bump wearing sustainable brand Losano

Michael Simon/Shutterstock

RELATED: Pregnant Rumer Willis Spotted with Boyfriend Derek Richard Thomas for First Time Since Announcing Baby

Rumer shared her pregnancy news days before Christmas with photos of her displaying her bump in a skintight black catsuit, including one snap of Thomas kissing her stomach.

She captioned the photo with a seedling emoji.

The mother-to-be is the oldest daughter of Bruce Willis and Demi Moore.

RELATED VIDEO: Rumer Willis Is Pregnant! Actress Expecting Her First Baby with Boyfriend Derek Richard Thomas

Moore recently gave her Instagram followers a glimpse of her daughter's journey to motherhood sharing a photo of a recent ultrasound appointment, where they were joined by Rumer's sisters Scout Willis and Tallulah Willis.

"Saying hello to the little nibblet!!" Moore, 60, captioned a photo on the appointment.

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

"Overjoyed for you, my sweet Rumer. It's an honor to witness your journey into motherhood, and can't wait to welcome this baby into the world!"