There are more reasons for delayed menstruation with wet and yellow underwear, which may be normal physiological phenomena, such as pregnancy, perimenopause, etc., or may be caused by pathological factors, such as pelvic inflammatory disease, endocrine disorders and so on. 1. Physiological phenomenon: (1) pregnancy: after pregnancy, estrogen and progesterone are rising, affected by pregnancy, secretions will also increase, a small number of pregnant women with minor infections will have wet yellow secretions. (2) perimenopause: age, ovarian function decline, fluctuating hormonal changes in the body, may cause delayed menstruation, some women with minor vaginal inflammation, such as geriatric vaginitis, there will be wet yellow discharge. 2. Pathological factors: (1) pelvic inflammation: chronic inflammation in the pelvis, such as chronic endometritis, or because of some other diseases, such as chronic appendicitis infection to the pelvis this situation, may cause menstrual disorders, accompanied by wet yellow discharge. (2) endocrine disorders: the recent stress reaction, excessive dieting and so on may cause menstrual delay, combined with vaginal or vulvar bacterial infection, may appear wet yellow discharge. There may be other reasons for delayed menstruation, so it is recommended to go to the hospital in time to improve the examination of secretions, blood human chorionic gonadotropin (HCG) test, ultrasound and other related examinations, and to clarify the cause of the disease under the guidance of a professional doctor, so as to provide targeted treatment.