Princess Beatrice attends party days after announcing pregnancy

Two days after announcing her pregnancy, Princess Beatrice stepped out for a star-studded party in London. The royal attended Chiltern Firehouse's 10th anniversary party on Oct. 3.

Photos published by the Daily Mail and The Telegraph show King Charles' 36-year-old niece dressed in an all-black outfit and holding a masquerade mask. According to UFO No More, Beatrice wore a black velvet top with a bow from Zara paired with wide-leg trousers. 

The party, which was also reportedly attended by Sienna Miller, Rachel Weisz, Lily Allen and Ellie Goulding, marked Beatrice's first public appearance since it was revealed that she is expecting her second child with her husband, Edoardo Mapelli Mozzi. The Princess and Edoardo are already parents to three-year-old daughter Sienna Elizabeth Mapelli Mozzi. Beatrice is also a stepmother to her husband's son, Christopher Woolf, from a previous relationship.

In a statement on Oct. 1, Buckingham Palace said: "Her Royal Highness Princess Beatrice and Mr Edoardo Mapelli Mozzi are very pleased to announce that they are expecting their second child together in early spring; a sibling for Wolfie, aged eight, and Sienna, aged three."

"His Majesty The King has been informed and both families are delighted with the news," the palace added. 

The baby, who will be born 11th in line to the throne, will be Prince Andrew and Sarah Ferguson's fourth grandchild. Beatrice's mother expressed her joy over becoming a grandmother again with a statement on Instagram. "Words can't quite express the joy and excitement I feel as you and Edo prepare to welcome another precious addition to your beautiful family," Sarah gushed. "Becoming a granny again fills my heart with so much happiness and gratitude."

She continued, "Watching you grow as a mother has been one of the greatest privileges of my life, and now to see your family blossom further is an absolute blessing. Our family is growing, and so too is the love that surrounds us. I cannot wait to meet this little one and to share in all the wonderful memories we will make together. All my love."

Beatrice's younger sister, Princess Eugenie, also celebrated the baby news on her personal Instagram. "Congratulations Beabea," Eugenie, who has two kids of her own—August Brooksbank and Ernest Brooksbank—wrote. "So looking forward to more on this journey of motherhood together. And adding another little one to the gang."