AMSTERDAM (Reuters) - Dutch Queen Beatrix, who turns 75 on Thursday, is expected to announce her abdication in favor of her son, Prince Willem-Alexander, in a hastily announced broadcast to the nation on Monday evening, Dutch media reported.

The address, scheduled for 7 p.m. (1 p.m. ET), was announced by the Royal Household, but no further details were released.

Queen Beatrix became the sixth monarch of the House of Orange in 1980 following the abdication of her mother, Queen Juliana, who reigned for 31 years.

Juliana was 73 years old and in deteriorating mental health when she abdicated but Beatrix has remained active and in good health despite some setbacks.

The queen was emotionally shaken when a man drove his car into a Queen's Day procession in 2009.

Her middle son, Prince Johan Friso, has been in a coma ever since he was buried in an avalanche while skiing last year.

(Reporting by Sara Webb and Anthony Deutsch; Editing by Robin Pomeroy)