Ivanka Trump and husband Jared Kushner welcomed their second child, a baby boy, on Oct. 15.
The daughter of real estate mogul Donald Trump, whom she co-stars with on "The Celebrity Apprentice" announced the birth on Twitter, saying, "We just welcomed a beautiful and healthy son into the world. Jared, Arabella and I couldn't be happier."
UPDATE: Trump, 31, shared a photo on her Tumblr page a photo of herself on a hospital bed, holding her new son.
"Please join in our joy as we welcome Joseph Frederick Kushner, named after each of our paternal grandfathers, both master builders of their generation and inspiring patriarchs of their families," she wrote.
"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," she added. "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."
Earlier in the day, she shared a photo of her two-year-old daughter, Arabella, on Instgram, saying, "Arabella is at home with her grandmother practicing her swaddle before her little brother comes home!"
Father Donald Trump also tweeted about the birth of his daughter's son, saying, "My beautiful daughter Ivanka just had a healthy baby boy. Jared and Ivanka are very proud!"
Until the birth of her son, Trump and Kushner kept the sex of their baby a secret, due to Trump's superstitions.
"I don't like to tell people, but I don't have the discipline to keep it a surprise," Trump said in Fit Pregnancy's October/November issue. "There are so many variables in motherhood that, those I can control, I like to."
Ivanka is the eldest daughter of Donald Trump's five children. She has an older brother, Donald Trump Jr., as well as three younger siblings, Eric Trump, Tiffany Trump and Barron Trump.