Princess Charlotte is poised to make history with the arrival of her new sibling—if the baby is a boy, that is.
Thanks to the Succession to the Crown Act 2013, Charlotte will be the first female royal in history not to lose her spot in line for the throne to a male heir if Kate Middleton gives birth to another boy.
Prior to the Succession to the Crown Act 2013, which was passed when Kate was pregnant with Prince George, a male heir would bump an older female out of her place in the succession line. The new rule, which applies to all royals born after October 28, 2011, dictates that succession based fully on birth order—not gender or sex.
Right now, Prince Charles is next in line for the throne after Elizabeth II is no longer queen. Then, Prince William is second in line with his children, George and Charlotte being third and fourth, respectively. While fifth in line is currently William's brother, Prince Harry, he'll be bumped to sixth when Kate Middleton gives birth to her and William's third child.
Consider this one small step for the two-year-old princess and one giant leap for the British monarchy.