Of King Carl XVI Gustaf’s four older sisters, only one has retained her Royal Highness status throughout her life – Princess Birgitta. And it’s all to do with now scrapped royal rules around weddings that changed everything for three of the ”Haga Princesses”.
The reason why Birgitta remained a Royal Highness while Princesses Margaretha, Désirée and Christina lost the styling upon their marriages is because of the Swedish constitution at the time. The law stated that Swedish princesses had to marry a man of equal rank or lose their royal status. Margaretha, Désirée and Christina all married commoners and gave up their royal rank. However, the Kings (first King Gustaf VI Adolf and then King Carl XVI Gustaf) gave them courtesy titles after their marriages – without the style of Royal Highness.
Their current titles are Princess Margaretha, Mrs Ambler; Princess Désirée, Baroness Silfverschiöld; and Princess Christina, Mrs Magnuson. They are not in the line of succession, nor are their children.
Princess Birgitta, on the other hand, married a man of equal rank – Prince Johann Georg of Hohenzollern. Therefore, she was able to retain her titles as he was also a royal. Like her sisters, she is not in the line of succession to the Swedish throne, nor are her titled children.
Since her marriage in 1961, Birgitta’s full title is Her Royal Highness Princess Birgitta of Sweden and Hohenzollern.
While these were the rules stipulated by the Swedish constitution at the time of the marriage of the four Haga Princesses (as they were commonly called), it is not the law in Sweden today.
Now, Swedish princesses can marry commoners and retain all their royal styles and titles. Crown Princess Victoria married Daniel Westling and remained the heir to the Swedish throne, and will one day be the Queen of Sweden. Daniel was even given the style of Royal Highness and title of Prince of Sweden. They have two children, Princess Estelle and Prince Oscar. Princess Estelle will also be the Queen of Sweden after her mother.
Her younger sister, Princess Madeleine, married Christopher O’Neill. She retained her royal titles and place in the line of succession. Their three children are also in the line of succession.