32-year-old William has finished his air ambulance pilot training earlier than expected and will be on unpaid leave until June 1.
"The Duke of Cambridge has completed the first phase of his in-work air ambulance helicopter pilot training with Bond Air Services earlier than anticipated," a spokesman for Kensington Palace was quoted as saying by The Telegraph.
It means that if the royal baby is born this week the Duke will have more than a month to spend at home with his wife and family.
Until now, it had been thought that Prince William would be training in Norfolk, Cambridge or Gloucestershire, the three places where he is training for his new job as a pilot with East Anglian Air Ambulance, leaving him facing an anxious drive back to London to be there for his baby's birth.
Instead, he is already by his wife's side at Kensington Palace and will be able to accompany her to hospital when she goes into labour.