Within minutes the happy announcement, made on the Swedish royal family's Facebook page, had received more than 5,000 likes.
"Princess Madeleine and Mr. Christopher O'Neill are delighted to announce that The Princess is expecting their second child," read the statement.
Princess Madeleine and Chris O'Neill married in June 2013
Since marrying in a fairytale wedding in June 2013, Madeleine and Chris have established themselves as one of the most popular royal couples. After the ceremony the dashing Anglo-American groom won over the Swedish people by giving his Valentino-clad wife several passionate kisses then punching the air with delight.
In a joint interview afterwards Madeleine reflected on the couple's idyllic honeymoon in the Seychelles and what a difference it made being married.
Searching for the right words, the princess said: "The sweetest feeling now that we are married is that we really are a team. It really brings a special… "bond," filled in Chris.
The new baby will be a brother or sister for Princess Leonore
Almost a year to the day after their nuptials Leonore was christened in the Royal Chapel at Drottningholm Palace in Stockholm with 160 guests in attendance. She wore the same cream gown that her cousin Estelle, the future queen, had on for her christening.
It will be an exciting time for the family as Madeleine's brother Prince Carl Philip is to wed his model love Sofia Hellqvist in a summer ceremony on 13 June next year.
The O'Neills live in New York, where Chris, a financier, runs his own business and his wife works for the World Childhood Foundation, an NGO founded by her mother, Queen Silvia.