The late Queen’s granddaughter, 36, and her husband Edoardo Mapelli Mozzi, 40, welcomed their second child a week ago on January 22 at the Chelsea and Westminster Hospital in London.
Beatrice and her daughter are now said to be at home, with the family enjoying spending time together with Athena’s older siblings, Wolfie, 8, and Sienna, three.
The King and Queen have been informed and are delighted, Buckingham Palace said.
The princess and her husband released a photograph of their daughter taken by Mr Mapelli Mozzi, showing Athena with dark hair, wearing a white long-sleeved garment, and wrapped in a pink blanket with her face hidden by her arm.
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Beatrice was due to give birth in early spring, and in December received medical advice and was told not to travel long distances.
She joined the royal family at church in Sandringham on Christmas Day after changing her travel plans to spend the festive period overseas, with doctors said to have warned that a premature arrival was a possibility.
In a statement issued on Wednesday, the Royal Family said: “Her Royal Highness Princess Beatrice and Mr Edoardo Mapelli Mozzi are delighted to announce the safe arrival of their daughter, Athena Elizabeth Rose Mapelli Mozzi, born on Wednesday, 22nd January, at 12:57pm.
“The baby was born weighing 4 pounds and 5 ounces. The King and Queen, and other members of The Royal Family have all been informed and are delighted with the news. Princess Beatrice and Mr Mapelli Mozzi would like to thank all the staff at the hospital for their wonderful care.
“Her Royal Highness and her daughter are healthy and doing well, and the family are enjoying spending time together with Athena’s older siblings, Wolfie and Sienna.”
The newborn is a little sister for the couple’s three-year-old daughter Sienna, and Mr Mapelli Mozzi’s son and Beatrice’s stepson, eight-year-old Wolfie.
Beatrice’s husband posted a tribute to his new daughter, calling her “tiny and absolutely perfect”.
Mr Mapelli Mozzi wrote on Instagram sharing a photograph of Athena wrapped in a blanket: “Athena Elizabeth Rose Mapelli Mozzi.
“We welcomed baby Athena into our lives last week. She is tiny and absolutely perfect.
“We are all (including Wolfie and Sienna) already completely besotted with her.
“Our hearts are overflowing with love for you, baby Athena.
“A massive thank you from my wife and I goes out to all the wonderful staff at the Chelsea and Westminster Hospital for their exceptional care and support during this incredibly special time.”
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Princess Beatrice’s sister Princess Eugenie celebrated the new arrival by posting “Welcome Baby Girl” and sharing Mr Mapelli Mozzi’s photograph of baby Athena on her Instagram Stories.
Her mother, Sarah, Duchess of York posted on social media: “Overflowing with love and joy to be able to welcome Athena Elizabeth Rose into the world.
“She is already so adored and I’m incredibly blessed to be a Granny once again.
“So proud of Edo, Beatrice and the rest of my little 5-a-side team.”
