What Causes Delay In Menstruation Other Than Pregnancy?

I am Malaya, my wife had started skipping before 45days,her period date is 2 to 5,but after doing skipping, there is disturbances of 12days.
i mean in the month of january the date was 2nd jan 2010, but in the month of feb the date is 17 feb 2010.

please say me there is any problem