A three-day delay in menstruation with abdominal pain may be a sign of pregnancy. A woman with a regular period who has a delayed period is most likely to be pregnant. After pregnancy, because the uterus is slowly enlarging, some people may experience pain in the abdomen, but the pain is a vague pain in the lower abdomen. If your period is delayed and you have lower abdominal pain, you should go to the hospital for a checkup, except for ectopic pregnancy, which can also cause lower abdominal pain when it ruptures, but the pain is very intense. If the result is two red bars, it proves that you are pregnant, but if it is one red bar, you can go to the hospital for a blood test, which is much more sensitive than the early pregnancy test and can detect pregnancy one week after the formation of the fertilized egg.