Agnès gave birth to three daughters fathered by the King: Marie de France, Charlotte de France, and Jeanne de France. While pregnant with their fourth child, she journeyed from Chinon in deep midwinter to join Charles on the campaign of 1450 in Jumièges, wanting to be with him as moral support. There, she suddenly became ill and died at the age of 28. While the cause of death was originally thought to be dysentery. In 2005 French forensic scientist Philippe Charlier examined her remains and found that the cause of death was mercury poisoning. This did not mean Sorel was murdered, because mercury was sometimes used in cosmetic preparations and also to treat worms. this could therefore have been the reason for her death.