"Isabella's mother, Elisabeth of Valois, gave birth to Isabella Clara Eugenia on 12 August 1566, & then to Isabella's younger sister Catherine Michelle 10 October 1567. Isabella did not get to know her mother, Elisabeth, who miscarried a son on 3 October 1568 & died the same day." http://bjws.blogspot.nl/2015/09/biography-isabella-clara-eugenia-of.html