Princess Eugenie, a daughter of Andrew Mountbatten-Windsor and Sarah Ferguson, is expecting her third child with her husband, Jack Brooksbank.
The baby is due this summer, Buckingham Palace announced Monday.
Eugenie and Brooksbank, who wed in 2018, are already the parents of 5-year-old August and 2-year-old Ernest.
The siblings are "very excited" for the new baby, according to the palace.
Eugenie shared a photo on Instagram Monday of August and Ernest looking at an ultrasound image, with the caption, "Baby Brooksbank due 2026! ♥️♥️♥️♥️♥️👶🏻♥️♥️♥️♥️♥️"
Eugenie is a niece of King Charles III, who is the older brother of Mountbatten-Windsor.
Buckingham Palace said Charles was informed of Eugenie's pregnancy and, "is delighted with the news." Eugenie and Brooksbank's third child will become 15th in the British royal line of succession.
Eugenie and her sister, Princess Beatrice, did not attend Easter service last month with other members of Britain's royal family.
The Easter service took place less than two months after their father, Mountbatten-Windsor, was arrested and released without charge on suspicion of misconduct in public office.
A royal source told ABC News that it was Eugenie and Beatrice's decision to not attend the Easter service on April 5, not the king's. The source said their decision does not mean they will not attend future royal family engagements.
Mountbatten-Windsor, formerly known as Prince Andrew, was stripped of his royal titles and honors by Charles last year, after stepping back from royal public duties in 2019. Both Eugenie and Beatrice have retained their titles and their places in the line of succession.
