The practice is believed to have begun in 1688, when dozens of officials watched Mary of Modena, wife of James II, give birth to a son, to scotch rumors that Mary was not really pregnant and that the baby was to be smuggled into the room in a bedpan.
The tradition continued well into the 20th century. The last royal birth to be witnessed by a government minister was that of Queen Elizabeth II's cousin, Princess Alexandra in 1936, and the practice was only officially halted shortly before the birth of Prince Charles in 1948.
Queen Elizabeth II
may not have had to contend with ministerial interference in her birth plan, but she also didn't have her husband there for support; while she gave birth to Prince Charles, Prince Philip, the Duke of Edinburgh
was busy playing squash.
Prince Charles was on hand when Diana had Prince William, but William himself may not be there for the birth of his second child -- expected any day now -- if he's at work when the big moment arrives.
If for any reason William can't get to the hospital on time, the Duchess of Cambridge may have her mother, Carole Middleton, there to support her instead.
Queen Victoria was the first royal to use anesthesia in childbirth
The long-reigning monarch and mother-of-nine was given chloroform for pain relief during the births of her eighth and ninth children, Prince Leopold (born in 1853) and Princess Beatrice (born in 1857).
Her decision to opt for an anesthetic is credited with popularizing the use of painkillers during childbirth among the well-to-do of the time.
John Snow, the doctor who administered the drug, is better known as one of the founding fathers of epidemiology, after he traced a deadly outbreak of cholera to a Soho water pump.
Prince William was the first heir to the throne to be born in hospital
William was born in the private Lindo Wing of St Mary's Hospital, Paddington, on June 21, 1982. His brother was born at the same hospital two years later, and Kate and William's first baby, George, was born there on July 22, 2013.
While that might seem the normal way of things, in fact it was something of a break with tradition -- until then, all heirs to the throne had been born at home (or at one of the royal family's homes at least).
Prince Charles was born at Buckingham Palace; Elizabeth II herself was born in the Mayfair home of her grandfather in 1926 -- though at the time she was not expected to become queen as her uncle, and not her father, was next in line to the throne.
Titled royal babies do not have surnames
Members of the royal family are famously burdened with plenty of names
-- Prince William was christened William Arthur Philip Louis, and his father is Charles Philip Arthur George -- but many (those titled His or Her Royal Highness) do not have a surname.
Prince William and Prince Harry used "Wales" at school and during their military careers, but this came from their father's official title as Prince of Wales.
As descendants of Queen Elizabeth II and the Duke of Edinburgh, they could also use Windsor, or Mountbatten-Windsor -- both of which are relatively new inventions, adopted during World War I to disguise the family's German origins.
When Prince George was born, William and Kate opted not to give him a surname -- officially he is Prince George Alexander Louis of Cambridge -- though when he and his new sibling go to school in a few years, they may use "Cambridge" as a last name.