The line for the royal throne may be a long one for Kate Middleton and Prince William's children, but, at least, Princess Charlotte's position won't be affected with the arrival of the couple's third baby.
She can thank the Succession to the Crown Act 2013, because for the first time ever, a female royal's spot won't be altered by the birth of a male. According to the new legislation—which was passed when Kate Middleton was pregnant with Prince George—birth order, rather than gender, determines the next king or queen of England.
Therefore, even if the third royal baby is a boy, he will have to wait his turn, directly behind the 2-year-old, to become king. The history-making motion also allows those arising from a marriage to a Roman Catholic to remain in the running—something that previously disqualified a budding royal.
However, that's not to say that Charlotte doesn't have quite a few years—possibly a lifetime–to wait until she will see her day as queen. Currently, Prince Charles, Prince William's father, will inherit the throne after Queen Elizabeth passes away. Respectively, Prince William is second, and then comes his children, Prince George (third) and Princess Charlotte (fourth).
Prince Harry's days in the fifth spot are limited, with the third royal baby due any day now. Once he or she is born, Harry will move down to sixth in line. In a universe that confuses most people with its traditions, things just got a whole lot less complicated.