The sudden absence of menstruation in the forties may be due to pregnancy, ovarian hypoplasia, systemic diseases and other reasons, which need to be analyzed specifically. 1. Pregnancy: If a woman in her forties has unprotected sex and her body can still ovulate, then it is possible that she is pregnant. 2. Decreased ovarian function: If a woman in her forties has symptoms associated with menopause accompanied by a lack of menstruation, it means that ovarian function has declined and estrogen secretion has decreased. 3. Systemic diseases: If hypothyroidism or tuberculosis exists, it may affect the body’s metabolism, thus affecting the normal pattern of hormone secretion and leading to sudden absence of menstruation. Forty-year-old women who suddenly do not have menstruation may also be related to endometrial inflammation, endometrial tumors and other factors, it is recommended to consult a doctor in a timely manner, under the guidance of the doctor to improve the relevant examination, to clarify the specific causes of the disease.