Katherine Schwarzenegger Excited for Her Girls to Grow Up with Rumer Willis' Baby: 'Like We Did'

Albert L. Ortega/Getty; Stefanie Keenan/Getty

Katherine Schwarzenegger Pratt is sharing excitement for a dear friend.

On Thursday, the children's book author and mom of two re-shared a powerful pregnancy post on Instagram that's gained attention recently detailing the physical and spiritual connection between mom and baby during gestation.

Schwarzenegger Pratt reshared the post from friend Rumer Willis, and took the opportunity to congratulate her friend on the recent news that she and boyfriend Derek Richard Thomas are expecting their first baby.

"So happy for my dear friend @rumerwillis who shared this and who is growing her beautiful babe," she wrote. "Can't wait for our kids to grow up together like we did."

The Good Night, Sister author shares her two girls, Eloise Christina, 6 months, and Lyla Maria, 2, with husband Chris Pratt.

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Willis and Thomas made their special announcement earlier this week with a carousel of bump photos.

In the first snap, the father-to-be wrapped his hand around her growing belly and gave it a sweet kiss while Willis smiled. She also showed off her pregnant silhouette as she stood near a window in another image. A photo that featured a very excited Thomas rounded out the set of pictures.

Willis' mom Demi Moore shared her excitement as a grandma-to-be when she too posted the announcement photos, writing, "Entering my hot kooky unhinged grandma era."

"So happy for you my love!" she later added in the comments.

RELATED: Pregnant Rumer Willis Joined by Mom Demi Moore and Sisters at Doctor's in Fun Family Photo

Rumer Willis/instagram

"Welcome to the club," Maria Shriver — Schwarzenegger Pratt's mom — wrote in Moore's comments.

The baby will be the first grandchild for Rumer's parents, Bruce Willis, 67, and Demi Moore, 60. The former couple also share daughters Tallulah, 28, and Scout, 31. The Die Hard actor is also dad to daughters Evelyn, 8, and Mabel, 10, whom he shares with wife Emma Heming Willis.

The tight-knit blended family appeared together in a Christmas family photo shared by Moore on Instagram in mid-December.

"We are FAMILY!! Getting into the holiday spirit!" she captioned the group shot.