UTI is an inflammation of the epithelial cells of the urinary tract and usually does not affect menstruation, but the opening of the urethra and the vagina are very close to each other, so UTI can easily cross-infection and cause gynecological inflammation, or a long-term, recurrent vaginal infection may also lead to urethral infection, so if a woman has a UTI and a gynecological infection at the same time, it may also affect her menstruation. Untreated vaginitis and UTI can cause upstream inflammation of the cervix or endometrium, or even pelvic and adnexal inflammation, which can easily lead to irregular menstruation. In addition, UTI treatment may also lead to irregular menstruation if anti-infective drugs are used for a long time and in large quantities.