Does Intake Of Unwanted 72 Cause Missed Periods?

Dr my gf n i had unprotected sex and she consumed unwanted 72 imm.. she checked on 29th of dec for pregnency n was negative. Her periods wer expected on 1st jan. But she still hasnt got them. What could be the problem. I req u plz could u mail me the ans and the things that could have possiblilly gone wrong.
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