'Million Dollar Listing New York' 's Fredrik Eklund Welcomes Daughter Milla and Son Fredrik

Fredrik Eklund is on double diaper duty!

The Million Dollar Listing New York star and husband Derek Kaplan have welcomed twins, daughter Milla Eklund and son Fredrik Eklund Jr., the new dad announced Tuesday on social media.

“Happiest moment of my life. Welcome Fredrick and Milla to the world,” Eklund captioned a snapshot of the new family of four.

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RELATED VIDEO: Twins on the Way for Million Dollar Listing New York‘s Fredrik Eklund

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Eklund and Kaplan first revealed they were expecting twins via surrogate during the season finale of MDLNY. “We’ve been blessed two times over – we’re six months pregnant with twins, a boy and a girl!” they later posted on Instagram.

“It was important for us to take the time to keep the news for ourselves, but now we are ready to celebrate all the love,” the couple added. “We thank you for supporting us in this journey and your well wishes … We are finally going to be dads! Finally! #grateful”

The spouses learned the good news in April while celebrating Eklund’s 40th birthday in Paris. “That was probably the biggest moment of my life,” he told PEOPLE in August. “I felt like it was meant to be, which is hard for me to say because it’s been so difficult.”

After their surrogate suffered multiple miscarriages, Eklund began feeling discouraged about in vitro fertilization. “It felt like every time I went onto Facebook or Instagram, all that I could see were these smiling babies on my feed,” he said in August. “I was reminded constantly that there was this gap between me and where I wanted to be.”

The Sweden-born, New York-based star also attributes his ability to persist through their struggles to his husband. “Derek was the best,” he added at the time. “He’s much more calm than I am.”

Since receiving their happy news, the couple has documented their growing collection of baby items on social media, including a nursery complete with embroidered pillows showcasing and pink and blue bunny blankets.

“We’re ready for you now … ” Eklund wrote in the caption of the photo.

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Eklund also shared an adorable photo of some newly purchased baby shoes, writing, “It’s okay if it snows this winter.”

While Milla and Fredrik are the couple’s first children together, Kaplan is already a dad to son Kai; about eight years ago, he donated his sperm to a couple he met in London, where the 7½-year-old now lives full-time with his moms.

“They’re little angels. I just can’t wait to finally hold them,” Eklund told PEOPLE ahead of his twins’ birth. “I think about them every minute of the day.”