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Firstly , 2 days before her expected periods its unlikely that she could be pregnant.
Secondly , she has taken an i pill
She must have had chances of menstruation
.They must have delayed for general reasons. As she has taken i pill now , she may have a delay in periods or intermittent bleeding as side effects.
I advise you not to take ipill
unnecessarily or frequently for the purpose of contraception
.It carries many side effects.