Princess Beatrice and Edoardo Mapelli Mozzi are expecting their second child together, with Buckingham Palace confirming the news on Tuesday 1 October.
Sarah Ferguson, Beatrice's mother, was quick to chime in on the public celebrations, taking to Instagram to share her excitement at becoming a grandmother again.
"A very proud GiGi/Mum today. Such an incredible blessing and an embrace to my heart," the former wife of Prince Andrew began. "Wolfie, August, Ernie and Sienna will be over the moon to have the fifth member of the five aside!"
Along with her sweet words, Sarah shared a previously-unseen photograph of Princess Beatrice and her daughter Sienna from the wedding of Marissa Montgomery and Jesse Brown at Chelsea Psychic Garden in June this year.
In the glorious summer snap, the York royal looked radiant wearing the 'Cordelia' silk crepe de chine tea dress from royally-loved brand Erdem. Complete with a whimsical floral print, elegant fluted sleeves and black criss-cross detailing on the bodice, Princess Beatrice's stunning gown looked beautiful on her feminine frame.
Adding to her enchanting wedding guest ensemble, the Princess wore a gypsophila flower crown woven into a botanical tiara. Her golden red hair was worn in a half-up, half down style, tumbling past her shoulders in elegant curls.
Princess Beatrice's rarely-seen daughter Sienna, three, was also seen in the photograph. The royal toddler looked adorable in a white ruffled dress fastened with a blue satin bow. Sienna's icy blonde curls looked so striking in the sweet family snap as she gazed up at her grandmother, Sarah.
Princess Beatrice's wedding guest looks
Princess Beatrice and her sister Princess Eugenie dominated fashion headlines during the wedding of Prince William and Kate Middleton in 2011. More than a decade on, the royal's swirling mauve fascinator crafted from a dramatic coiled ribbon, has remained just as memorable as it was on the day.
At the royal wedding of Prince Harry and Meghan Markle in 2018, Beatrice was a vision in an ornate embellished teal dress by Roksanda, paired with Stephen Jones hat and Gianvito Rossi heels.
Just a few months later, Beatrice served as maid of honour at her sister's wedding at St. George's Chapel in Windsor Castle on Oct. 12, 2018.
Beatrice looked every inch the part in a royal blue dress with asymmetrical neckline by London-based couture house Ralph & Russo along with a blue-and-purple headpiece by British milliner Sarah Cant.