sir/ ma'am i usually get prepone mc last month day was 21 but this month i din't get get my period yet. & i checked through the pregnancy test kit resulted i am not pregnant. & i am taking the treatment of hapetitis b (pegasys 180mcg) so what can be the cause for that delay of period.....please help me i am very worried about it. & i dont have the problem like thyroid or else.