Dwayne 'The Rock' Johnson, girlfriend Lauren Hashian welcome 'strong' baby girl Tiana

Anika Reed | USA TODAY

Show Caption Hide Caption What is Dwayne Johnson thankful for? With his surprise baby news just announced on Monday, we asked Dwayne The Rock Johnson to write down what he is most thankful for this holiday season. His answer surprised us, and probably everyone in his family.

Dwayne "The Rock" Johnson officially has a new addition to his "mana."

The actor and professional wrestler took to Instagram on Monday to celebrate the birth of his daughter with girlfriend Lauren Hashian.

"Blessed and proud to bring another strong girl into this world," Johnson writes in the caption. "Tiana Gia Johnson came into this world like a force of nature and Mama [Lauren Hashian] labored and delivered like a true rockstar."

Johnson and Hashian first announced the news that they were expecting a baby girl in December, with an adorable Instagram post featuring his and Hashian's first daughter together, Jasmine Lia.

Johnson praised Hashian's strength in the delivery room in the post, writing: "I was raised and surrounded by strong, loving women all my life, but after participating in baby Tia’s delivery, it’s hard to express the new level of love, respect and admiration I have for [Hashian] and all mamas and women out there."

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Johnson, 45, also offered up some wise words for future parents: "If you really want to understand the single most powerful and primal moment life will ever offer - watch your child being born. It's a life changer and the respect and admiration you have for a woman, will forever be boundless."

"You have my word," Johnson says to his new daughter in the post, "I’ll love, protect, guide and make ya laugh for the rest of my life. Your crazy dad has many responsibilities and wears many hats in this big ol’ world, but being your dad will always be the one I’m most proud to wear."

USA TODAY has reached out to Johnson's reps for comment.

Johnson has another daughter, Simone Garcia Johnson, from his earlier marriage to Dany Garcia.

The Rock thanks medical professionals who tended to his two-year-old during an emergency