Spain's Crown Prince Felipe, second right and Princess Letiizia pose with their daughters Sofia, left and Leonor, right in their official residence in Madrid. Spanish Princess Letizia celebrated her 40th birthday on September 15. (AP Photo/Spanish Royal Palace/Cristina Garcia Rodero)

Spain's Princess Letiiz, centre poses with her daughters Leonor, left and Sofia in their official residence in Madrid. Spanish Princess Letizia celebrates her 40th birthday on September 15. (AP Photo/Spanish Royal Palace/Cristina Garcia Rodero)

Spain's Princess Letiiz, right poses with their daughters Leonor, left and Sofia in their official residence in Madrid. Spanish Princess Letizia celebrated her 40th birthday on September 15. (AP Photo/Spanish Royal Palace/Cristina Garcia Rodero)

Spain's Crown Prince Felipe, right and Princess Letiizia, left pose with their daughters Sofia, 2nd left and Leonor, 2nd right in their official residence in Madrid. Spanish Princess Letizia celebrated her 40th birthday on September 15. (AP Photo/Spanish Royal Palace/Cristina Garcia Rodero)

Spain's Crown Prince Felipe, right holds his daughter Leonor while Princess Letiiz left, sits with their other daughter Sofia in their official residence in Madrid. Spanish Princess Letizia celebrated her 40th birthday on September 15. (AP Photo/Spanish Royal Palace/Cristina Garcia Rodero)

Spain's Crown Prince Felipe and Princess Letiiz, right pose with their daughters Sofia, left and Leonor, 2nd left in their official residence in Madrid. Spanish Princess Letizia celebrated her 40th birthday on September 15. (AP Photo/Spanish Royal Palace/Cristina Garcia Rodero)

Spain's Crown Prince Felipe, second left and Princess Letiiz pose with their daughters Leonor, left and Sofia, right relax in their official residence in Madrid (AP Photo/Spanish Royal Palace/Cristina Garcia Rodero)

Spain's Princess Letiiza poses in her official residence in Madrid. Spanish Princess Letizia celebrated her 40th birthday on September 15. (AP Photo/Spanish Royal Palace/Cristina Garcia Rodero)

Spain's Crown Prince Felipe, right and Princess Letiiz pose in their official residence in Madrid. Spanish Princess Letizia celebrated her 40th birthday on September 15. (AP Photo/Spanish Royal Palace/Cristina Garcia Rodero)

Spain's Crown Prince Felipe, right and Princess Letizia pose in their official residence in Madrid. Spanish Princess Letizia celebrated her 40th birthday on September 15. (AP Photo/Spanish Royal Palace/Cristina Garcia Rodero)