Hello dear I understand your concern Postinor 2 contain high progesterone and it cause following side effects: Breakthrough bleeding, delayed period/earlier period, excessive bleeding in period, nausea, diarrhea, breast soreness and tiredness. It is 90-95 % effective in preventing the pregnancy (If taken with in 24 hour of the sex). If you have sex in the fertile phase of the cycle (10th to 20th day of cycle) then chance of the pregnancy. Otherwise delayed period is due to high progesterone in the pill that prolong the second phase of the cycle. If your period will delay by 14th day from the normal expected period date then go for pregnancy test and or blood HCG to confirm the pregnancy. Avoid stress, take healthy diet and drink plenty of water Hope this may help you Contact HCM for further health query Best regards Dr. Sagar