The lack of menstruation generally refers to the delay of menstruation, the basal body temperature is lowered and whether the menstruation is delayed generally does not have much to do with the delay of menstruation may be pregnancy, endocrine disorders, endometritis and other reasons. 1. Pregnancy: If a woman has not been using contraception for a while and has a normal sex life, delayed menstruation may be due to pregnancy. After pregnancy, the hormone levels in the body change rapidly, and the uterine lining is no longer shed, so there will be no menstruation. 2. Endocrine disorders: Suffering from endocrine disorders will lead to estrogen and progesterone disorders in the body, which will affect the normal menstrual cycle, so women will experience delayed menstruation. 3. Endometritis: endometritis is an infectious disease, after local inflammation, it will lead to endometrial congestion, edema, and some purulent secretions, resulting in delayed menstruation. In addition, endometrial dysplasia, endometrial injury, pituitary gland dysfunction, etc., may lead to delayed menstruation even though the basal body temperature has been lowered, so it is recommended to go to the hospital for a comprehensive examination to clarify the cause.