(Reuters/Lefteris Pitarakis)Britain's Prince William and Catherine, Duchess of Cambridge, arrive at a reception in aid of the National Memorial Arboretum Appeal at St James's Palace, London, November 10, 2011.

Kate Middleton and Prince William's first child is due in July, St. James' palace confirmed Monday. The news comes just days after The Queen of England's formal decree.

The Duchess of Cambridge, who announced that she is expecting in December, is said to be in much better health following her recent hospitalization. Both she and the Duke of Cambridge, 30, are said to be thrilled with the baby news.

"Their Royal Highnesses the Duke and Duchess of Cambridge are delighted to confirm they are expecting a baby in July," a St James' Palace spokesman said. "The Duchess's condition continues to improve since her stay in hospital last month."

Middleton was hospitalized on Dec. 3 after suffering from hyperemesis gravidarum, a condition that causes severe vomiting during pregnancy. She was admitted for three days and is reportedly close to making a full recovery.

The baby news follows a formal decree made Thursday by The Queen which states that the couple's first born will hold the formal title of prince or princess, depending on its gender. The baby will also be referred to as His or Her Royal Highness, according to People magazine.

"The Queen has been pleased by Letters Patentunder the Great Seal of the Realm dated 31 December 2012 to declare that all the children of the eldest son of the Prince of Wales should have and enjoy the style, title and attribute of royal highness with the titular dignity of Prince or Princess prefixed to their Christian names or with such other titles of honour," a declaration signaled in The London Gazette stated.

The Duke and Duchess, who have been married almost two years, sparked rumors that they were expecting twins after Middleton was hospitalized with hyperemesis gravidarum. The condition causes severe vomiting in pregnancy, and is more prevalent in women who are pregnant with twins.

It is unclear how exactly the Queen's decree would be enforced if the couple does in fact have twins. However, a former schoolmate of Middleton confirmed that twins for the couple would still be "a dream come true."

"Catherine would love twins and a lot of people in their circle in London say it could indeed be the case that she is expecting twins," Jessica Hay, who once shared a dorm with Middleton at Marlborough College, told Australian magazine New Idea. "If it were a boy and a girl, it would be a dream come true for them both."