In the New York Times, above Charlotte and Harry's engagement announcement it displays the engagement announcement of Natasha and Mr Big, which Charlotte reads to Carrie in the episode 'Attack of the Five Foot Ten Woman'.
In the New York Times announcement for Charlotte and Harry's wedding, it is written that she is a writer/editor for 'Fashions' magazine (something never mentioned in the show), her father is a doctor, her mother's nickname is 'Muffin' and she is a descendent of Samuel Huntington, who signed the Declaration of Independence.