If the menstrual period has been delayed for three days, there is pain in the stomach, may be related to the following factors: First, may be coming to menstruation, the pelvis is in a state of congestion, the stomach will have a slight pain, and this pain will not affect the daily work and life, as long as you rest a little on it, and patiently wait for the onset of menstruation. Secondly, if you have normal sexual life without contraception, it may be caused by pregnancy. However, when the menstrual period is delayed for 3 days, only through the blood test of blood HCG can we know whether we are pregnant or not, often at this time through the urine HCG test does not give a positive result, so this point should be noted. Because of individual differences, everyone feels differently after pregnancy, some people may have a vague uncomfortable feeling in the lower abdomen or even pain when they are just pregnant, while some people do not have any uncomfortable feeling, so it is recommended to rule out the possibility of pregnancy first.