Can prostinor 2 change my menstrual cycle?

Yes!: Your period might be different. Most women will have a normal period at the expected time, but some may have their period later or earlier than normal. You might also have some irregular bleeding or spotting until your next period. If your period is more than 5 days late or is unusually light or unusually heavy, or especially painful, you should contact your doctor as soon as possible.

Theoretically yes: Since it is a Progesterone inhibitor, yes, too frequent use can lead to menstral cycle...Only theoretically speaking.