The main causes of reduced menstruation include: 1, endocrine disorders, estrogen reduction, resulting in reduced menstruation; 2, chronic wasting diseases, such as tuberculosis, hypothyroidism, tumors, can lead to endocrine disorders, estrogen reduction, resulting in menstruation; 3, the role of drugs, such as the gastric power drug morpholine can cause menstrual disorders; 4, excessive weight loss: diet pills can lead to endocrine disorders, resulting in low or no menstruation and amenorrhea; 5, mental factors: excessive sadness, grief and anger, impatience can lead to endocrine disorders, thus affecting menstruation.