Ivanka Trump barely showed a bump at her 'Fit Pregnancy' cover party on Sept. 17 in New York City.
(Photo: Michael N. Todaro, Getty Images)
"We welcome with love, Joseph Frederick Kushner," Ivanka Trump wrote on her Tumblr pageTuesday, along with a photo of her new son, born Monday night.
The newly expanded family -- including Trump's husband Jared Kushner and their daughter Arabella, 2 -- also explained the meaning behind the baby's name.
"Jared's grandfather, Joseph, was a rock. His indomitable spirit, his sense of family, and his work ethic are the values we hope to hand down to our son. My grandfather, Frederick, was a builder not just of tens of thousands of homes throughout this city, but of a tight-knit family that honors to this day the traditions he established.
Both men set the standards that have been passed down through the generations and which we hope to impart upon Joseph and Arabella. They created a legacy for our family that inspires our careers as well as our love and respect for one another. We are honored to name our son after these two distinguished men. We feel so blessed with the newest member of the family!"
Trump tweeted the happy news of Joseph's arrival late Monday.
"We just welcomed a beautiful & healthy son into the world," the jewelry designer and Celebrity Apprentice boardroom judge tweeted at 11:39 p.m. ET. "Jared, Arabella and I couldn't be happier!"
Grandpa Donald Trump also chimed in on Twitter to confirm the news: "My beautiful daughter Ivanka just had a healthy baby boy. Jared and Ivanka are very proud! Thanks to all for the wonderful congratulation sent to me on the birth of Ivanka's little boy - so nice!"