Kate Middleton wants to have a third child before she turns 35 after Buckingham Palace announced she was expecting hers and Prince William's second.
Friends of the duchess, 32, claim she wants at least one more child after Prince George gains a new brother or sister in either April or May next year, reports the Telegraph.
It means the royal couple could try for another baby within two years after having their first last year.
Prince Charles today spoke for the first time since news broke of the pregnancy at a Prince's Trust Enterprise Programme in south London.
Talking to Elizabeth Owoseje, mother of entrepreneur and furniture designer Demi Owoseje, the Prince of Wales responded to wishes of congratulations by joking: "What have I done? It has not arrived yet."
The heir to the British throne then said the duchess's pregnancy was "rather splendid".
In the wake of the early announcement, which made headlines across the globe, Her Royal Highness pulled out of a trip with her husband to Oxford after suffering from acute morning sickness.
Prince William said he and his wife were "thrilled" at the fact they are expecting their second child, who will become fourth in line to the throne regardless of its sex.
In other news, the odds on the duchess giving birth to twins have been slashed to 10-1 with one bookmaker after a punter laid down a £1,000 bet.
The bookies believe the couple will have a girl.