When menstruation does not come for two or three months during puberty, it may be related to immature ovarian development, drug stimulation, emotional stimulation, anemia, hyperthyroidism, early pregnancy and other conditions. 1. Ovarian immaturity: As the body of adolescent girls is still in the developmental stage, the development of the ovaries is not up to the standard of adult women, a few girls may have irregular menstrual cycles, and with the gradual development of the ovaries, menstruation will become more and more regular. 2. Drug stimulation: If a girl has recently taken amiodarone, emergency contraceptive pills and other drugs, it will affect the endocrine, resulting in menstrual cycle disorders. 3. Emotional stimulation: If the girl has recently been under mental stress or study pressure, excessive tension or anxiety, it may affect the cerebral cortex, leading to menstrual cycle disorders. 4. Anemia: If an adolescent girl is malnourished, or if other factors lead to severe anemia, it can lead to delayed menstruation. 5. Hyperthyroidism: If a girl has hyperthyroidism, it may lead to delayed menstruation due to the stimulating effects of thyroid hormones. 6. Early pregnancy: If an adolescent girl has had sexual intercourse and did not use contraception during sexual intercourse, accompanied by symptoms such as an enlarged abdomen, nausea and vomiting, she may be pregnant. Therefore, if adolescent menstruation does not come for two or three months, it is recommended to go to the hospital in time, after a clear diagnosis, follow the doctor’s instructions for treatment, so as not to miss the condition.