If you take emergency contraceptive pills, menstruation delayed 7-10 days has not come, there are two possibilities: 1, contraceptive pills did not achieve the remedial effect, unwanted pregnancy, so menstruation can not come normally, generally more than 12 days after intercourse or more than 10 days to the hospital to take a blood test for HCG, or take a pregnancy test stick to measure, to rule out the possibility of unwanted pregnancy. 2, contraceptive pills in the dose of progesterone is particularly large, it is possible to Delayed ovulation, or delayed ovulation, abnormal ovulation, so that a cycle does not ovulate to achieve remedial effect, may make the menstrual cycle disorders, so that menstruation can not be normal, the impact on menstruation will be half a month to 20 days or even longer, will come to the normal menstruation.