Many women adopt different contraceptive methods to prevent pregnancy. Some of which may cause bleeding/spotting at irregular intervals. Seeing as this form of bleeding is not a period, because it works by preventing the release of the egg from the ovary, basically they stop ovulation, would a woman be considered unclean? The irregularity could be as little as seeing a spot of blood when using the toilet once a week.
Would the policy on menstruation apply here?
Please bear in mind that the choice of contraception is often influenced by a number of factors such as; age, weight, nursing a child, family planning, allergies etc