For women who have sex and are not using contraception, if there is no menstruation for 45 days, the possibility of pregnancy can be considered. In addition to the manifestation of no menstruation, there may also be early pregnancy reactions, such as nausea, vomiting, weakness, drowsiness and other symptoms, which can be confirmed by blood HCG. However, the reasons for 45 days of no menstruation are not limited to pregnancy, but also include the following reasons: 1. Pathological factors: menstruation is easily affected by emotions and environment, if hormonal disorders, so that the ovaries secrete low levels of estrogen and progesterone, menstruation is delayed or even amenorrhea occurs. Diseases such as polycystic ovary syndrome, premature ovarian failure, uterine adhesions, hyperprolactinemia or pituitary adenoma can interfere with the normal hormone secretion, resulting in delayed menstruation and 45 days without coming. 2. Other factors: long-term dieting, staying up late, mental stress, taking birth control pills or diet pills, etc. can also cause delayed menstruation. If there is no menstruation for 45 days, you should go to the hospital for relevant examinations, including sex hormone examination, blood HCG examination, imaging examination, etc., to clarify the diagnosis and then deal with it according to the examination results.