The Duke and Duchess of Cambridge's baby is due in July, St James's Palace announced today.
Kate's condition is also continuing to improve following her stay in hospital last month for severe morning sickness, a spokesman for the couple said.
The Duchess is believed to be around 13 to 14 weeks pregnant and confirmation of the birth month means it is likely she has now had her 12-week scan.
"Their Royal Highnesses the Duke and Duchess of Cambridge are delighted to confirm they are expecting a baby in July," a St James's Palace spokesman said.
"The Duchess's condition continues to improve since her stay in hospital last month."