3. A number of public officials used to attend the royal births, including home secretaries.
Home Secretary Sir William Joynson-Hicks was present at the queen's birth in 1926. There were reportedly 42 eminent public figures called in to verify the birth of King James II's son James Francis Edward in 1688 at St James's Palace.
4. The royal baby will be third-in-line to Britain's throne, after Prince Charles and Prince William, regardless of whether it is a girl or a boy.
In April of this year, the U.K. changed its rights of succession, ending centuries of male primogeniture. The little prince or princess will push Prince Harry into fourth place in the line of succession.
5. The last time a still-serving monarch was alive at the birth of his or her great-grandchild in direct succession was 120 years ago.
That was the birth of Queen Victoria's great-grandson, the future Edward VIII, in 1894. He abdicated the throne in 1936.
6. The birth of Prince William and Kate's child will be announced via a bulletin that will be placed on an easel in front of Buckingham Palace.
It is custom for news of royal births and deaths to be attached to the railings of Buckingham Palace. William's was the first royal birth bulletin to be placed upon the easel.
The bulletin, which will state the baby's time of birth, gender and weight, will bear the Buckingham Palace letterhead and be signed by key medical staff. This will be the nation's first chance to find out if it is a boy or a girl.
7. Some economists expect the birth to boost the U.K. economy by $380 million.
8. The queen showed off royal babies William and Harry on the balcony at Buckingham Palace in front of huge crowds.
9. Of Britain's 40 sovereigns since 1066, just six have been queens.
According to Paddy Power, Alexandra was the favorite girls' name as of Friday morning, with 7/4 odds. Charlotte is the second-favorite, with odds of 5/1. As for boys' names, George has 5/1 odds, and James has 8/1.
The bookmaker is also taking bets on the baby's hair color, date of birth, weight, first word and -- no joke -- age at first nightclub visit photograph.