Hello dear I understand your concern If birth control pill was taken regularly without missing pill then chance of pregnancy is only 0.5%. 3 day delayed period occasionally considered as normal. Wait for period to come. If period will delay by more then 7 days from normal expected period date then go for urine pregnancy test and or blood HCG test to confirm pregnancy. In absence of pregnancy, delayed period could be due to stress, change in life style & dietary habit, ovarian dysfunction. Avoid stress, take healthy diet, drink plenty of water and do regular exercise. Hope this may help you Contact HCM for further health query Best regards Dr. Sagar