“Her name is part of English and Portuguese history, two places we love and call home,” Eugenie said in a post.
Annina relates to a personal connection, although Eugenie has not publicly provided further details.
The baby’s first name Adelaide is part of the couple’s history, as eagle-eyed observers have noted nods to the name at their 2018 wedding.
As per People magazine, Eugenie wore accessories that belonged to Queen Adelaide on her wedding day in 2018, including two diamond brooches in her hair commissioned by William IV for his wife, which Eugenie wore to her wedding reception.
Additionally, the couple was married at St George’s Chapel, in Windsor Castle, where Queen Adelaide is buried.
Baby Adelaide, who is 15th in line to the throne, was born in Lisbon, Portugal, on August 3.
“Augie and Ernie are already the best big brothers,” Princess Eugenie shared in her latest social media update.