What Causes Delayed Period After Taking COR 3?

A GYNOCOLOGIST HAS GIVE COR 3 TABLET TO MY WIFE. AND SHE MISSED HER PERIOD THIS MONTH. WE TESTED FOR PREGNANCY BUT IT HAS COME NEGATIVE. SHE HAS NOT GOT HER PERIODS THIS MONTH WHICH WERE SUPPOSE TO HAPPAN ON 31.01.2015. IS THERE ANY SERIOUS PROBLEM. HAS SHE MISSED HER PERIODS BECOZ OF THE MEDICINE. PLS HELP ME AND WHAT NEEDS TO BE DONE NOW SHOULD WE CONSULT THE DOCTOR OR DO WE NEED TO WAIT TILL THE NEXT CYCLE.