If you have a regular menstrual cycle and suddenly experience menopause, it may be due to the following reasons: 1. If you have a normal sexual life without contraception, the sudden menopause may be caused by pregnancy. It is advisable to collect morning urine for early pregnancy test to rule out the possibility of pregnancy. 2. The endocrine disorder, such as sudden cold stimulation or great emotional fluctuations, can lead to menopause. 3. If you lose weight and are not planning to lose weight, sudden weight loss, when the fat content is less than 20% of the total weight, can also lead to menopause. It is advisable to have a detailed examination, and if it is caused by endocrine disorders, it is recommended to take oral medication for regulation. If it is caused by weight loss, it is recommended to stop losing weight and eat normally.