Can Duphaston Tablet Affect Normal Menstrual Cycle?

I had my follicular study done. My ovulation happened on 20 Feb. This is when we went intimate. My doc has given me duphaston since then twice a day. I tested pregnancy on 8 march which was negative. I am still taking duphaston as per doctors suggestion.will duphaston interfere with my normal mensuration cycle if I m not pregnant. As I HV been experiencing blood spotting from few days.