Philip received his name in honour of the King Philip II of Spain. The birth was celebrated with great joy by all the court, because thus was secured the succession of the Grand Duchy for another generation and eliminated all the hopes of Bianca Capello (his father's mistress) to have her "son" Antonio as heir of Tuscany. Philip became Grand Prince of Tuscany.
When he was only one year old, his mother died in an accident falling down the stairs of the duchal apartments while heavily pregnant. His father then married Bianca Capello. Philip was one of seven children, but only two of the children survived till adulthood, Eleonora de' Medici and Marie de' Medici (who became queen consort of France). He had another sister Anna who died aged fourteen. Philip died on 29 March 1582; he was four years old, and suffered from hydrocephalus: when his skull was opened, the equivalent of about a glass of water came out. Recent study of his remains have confirmed the diagnosis.
^, Gino Fornaciari, Angelica Vitiello, Sara Giusiani, Valentina Giuffra, Antonio Fornaciari, Natale Villari, The Medici Project: First Anthropological and Paleopathological Results. (retrieved 23 January 2011).