Sixteen-year-old delayed menstruation may not come with endocrine disorders, pregnancy, reproductive organ development malformation, chromosomal abnormalities and so on have a certain relationship. 1. Endocrine disorders: sixteen-year-old girls ovarian function development is not yet perfect, estrogen level is not stable, may cause delayed menstruation phenomenon; but some girls due to mental stress, irregular work and rest, excessive learning pressure, poor eating habits, environmental changes and other physiological factors, may also lead to endocrine disorders, delayed menstruation phenomenon. 2. Pregnancy: For sixteen-year-old girls, there may be a history of sexual intercourse without contraception, delayed menstruation, the possibility of pregnancy. 3. Abnormalities in the development of reproductive organs: some women have abnormalities in the development of reproductive organs such as vaginal atresia, congenital uterine development disorders, vaginal diaphragm, etc., which may lead to obstruction of the menstrual outflow tract, thus manifesting the phenomenon of absence of menstruation. 4. Chromosomal abnormalities: generally seen in primary amenorrhea, mostly refers to women at 16 years of age without menarche, no breast development, or 18 years of age, although there is breast development, but no menstruation, especially with Turner’s syndrome, androgen insensitivity syndrome, most of the chromosomal abnormalities lead to. There are many reasons for delayed menstruation at the age of sixteen, so it is advisable to go to the hospital in time for ultrasound of the uterine adnexa, human chorionic gonadotropin and other tests to determine the cause of the disease and then targeted treatment.