The pain in the stomach three days after intercourse is not an inevitable manifestation of pregnancy, and usually pregnancy does not have a similar situation, more need to consider whether there is a urinary system and gynecological related infections, as follows: 1. Infection: It is recommended to temporarily abstain from sex and go to urology or obstetrics and gynecology clinic to check urinalysis, urological ultrasound, gynecological ultrasound, vaginal discharge, etc. 2. Pregnancy: It is recommended to regularly monitor blood and urine HCG, especially when there is no safety measures for sexual intercourse, if pregnant, usually in two weeks or in about a month can have HCG elevation. According to the test results, appropriate treatment options should be chosen, such as urinary tract infection, which may require symptomatic anti-infection treatment, as well as drinking more water, and if the general antibiotic treatment is ineffective, bacterial culture and drug sensitivity test of the relevant secretions should be performed if necessary.