Charles is listed at 14-1 as bets on a boy increased in last week.
"All I want to do is make my mother incredibly proud," Prince Harry said.
President Donald Trump and First Lady Melania Trump will meet Queen Elizabeth II on Friday.
Diana responded: "That's rich! They get to decide whether I divorce."
Princess Diana turned to Queen Elizabeth II for help during her marital struggles with Prince Charles, soon-to-be-aired tapes reveal.
In an interview with Newsweek, the British prince explains how he found a way to give his life meaning after struggling to cope with the death of his beloved mother, Princess Diana.
A series of newly announced documentaries and news specials illustrate Princess Diana's enduring legacy in the United States.
Cluster bombs, chemical weapons and other banned weapons are now commonplace.
Image of Diana's solo visit came to symbolize her unhappy marriage to Prince Charles.
Of all her roles, being a mother seemed to be the one Diana loved most.
The royal anti-land mine crusader brought to light the human side of the damage the devices wrought.