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Game of Thrones ' Hafþór Júlíus Björnsson Welcomes a Son: A 'Healthy, Strong, Beautiful Boy'

Hafþór Júlíus Björnsson/Instagram Hafþór Júlíus Björnsson and Kelsey Henson

The Mountain is a dad!

Hafþór Júlíus Björnsson — best known for his role as Gregor "The Mountain" Clegane on Game of Thrones — and wife Kelsey Henson welcomed their first child together, a baby boy, on Saturday, the couple announced on Instagram.

"Our beautiful baby boy made his grand entrance into the world at 11:19 AM on September 26th 2020 after a short and intense six hours. 3530 grams and 52 cm. The birth was the most powerful, life changing, empowering thing I’ve ever done in my entire life. We are all doing well and settling in at home as three!" the new mom shared on Sunday.

The actor also shared the story of their son's birth. "After an extremely hard 2 hours and 19 mins of pushing our healthy, strong, beautiful boy arrived weighing 3530 grams, 52 cm long," he said. "To finish the most beautiful, awe inspiring labour was the most wonderful phone call to my daughter to introduce her to her new little brother."

Björnsson is also dad to daughter Theresa Líf, whom he shares with his ex-girlfriend Thelma Björk Steimann.

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26.09.2020 . 6am Kelsey woke me up telling me she had been losing her water, I immediately jumped out of bed and said alright let’s go, she stayed calm and replied with a laugh and said, no we are not going yet. I then asked to call our midwives to which she replied again no let’s just wait for awhile. . 7:15am we call our friend to come photograph the labour, the midwife and doula. Once the midwife arrived she checked out the progress and we were surprised to learn Kelsey was already 5cm dilated. The midwife asked if she was ready to go to the birthing centre or wanted to try out that bath at home and Kelsey, still remaining calm, decided to try the bath at home. While I was filling up the bath things started escalating quickly, the contractions were much stronger lasting over a minute and were anywhere from 2-3 min apart. The midwife then said she thought we should head to the clinic and finally Kelsey agreed it was time. . 8:40am. We arrived at the Björkin, the birthing centre, after a quick 10 min drive. Right away Kelsey knew exactly what she wanted and asked how long until the birthing pool would be filled. The next fifteen minutes Kelsey paced around between contractions waiting for the tub to be filled. . 9:00am She was in the tub and immediately started to push. Things escalated super quickly. Throughout it all she did amazing. She was in complete control of her mind and body. She had strong opinions on exactly what she wanted and where she wanted to be. I am completely in awe of how strong she is, and so proud of her for everything she did to prepare herself throughout her pregnancy. It cannot be put into words how proud I am and how I feel about this experience. . 11:19am After an extremely hard 2 hours and 19 mins of pushing our healthy, strong, beautiful boy arrived weighing 3530 grams, 52 cm long. . To finish the most beautiful, awe inspiring labour was the most wonderful phone call to my daughter to introduce her to her new little brother ❤️ . 5:30pm We arrive back at home both mom and baby doing super well and spent our first night as three together. . We have decided on a name and cannot wait to share it with you all soon.

A post shared by Hafþór Júlíus Björnsson (@thorbjornsson) on Sep 27, 2020 at 2:38pm PDT

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Björnsson announced Henson's pregnancy in April, alongside photos from their "gender reveal" party. The actor, 31, and his wife learned the sex of their baby by popping a large black balloon, from which burst blue confetti.

"Swipe right to see gender of the mini me! 😱," Björnsson wrote alongside a series of photos that showed the then-parents-to-be beaming with joy.

Björnsson and Henson (who are 6 ft., 9 in., and 5 ft., 2-in., respectively), showed off their excitement with their hands in the air, smiling from ear to ear.

In another photo, the two shared a sweet kiss and were seen looking lovingly at one another after finding out the big news.

Björnsson and Henson celebrated their son on the way in early August at a sweet baby shower full of gifts and fun games — which the actor joined in on!

"My beautiful wife is 31 weeks + 2 days pregnant! 😍 I couldn't be more proud of you @kelc33 ❤️," he captioned a photo of the pair, in which he cradled her baby bump lovingly while she wore a sash reading "Mom to Be."

The GoT star and Henson tied the knot in October 2018 in his native Iceland.

"It is with great pleasure that I now get to call Kelsey Morgan Henson my wife!" Björnsson captioned a photo of himself holding his bride up on their wedding day.