A normal woman’s period is once a month, but many factors may cause a woman not to have a period, including pregnancy, stress, cold, radiation, drug abuse, constipation, and many other reasons. When a woman is pregnant, her period will not come back because the pregnancy capsule has already laid on top of the uterine lining and changes such as estrogen and progesterone are therefore impossible to shed. If a woman is under stress for a long time, it will cause abnormal secretion of the pituitary gland, which will affect the ovaries’ secretion of female hormones and no longer ovulate, thus causing menstrual disorders or even non-arrival. Many women do not pay attention to warmth during their periods, and the cold will cause vasoconstriction in the pelvic cavity and ovarian dysfunction, which over time will cause amenorrhea. Radiation interference is also an important factor for not coming to menstruation. If you are affected by radiation or electromagnetic waves for a long time, then these radiations will affect women’s endocrine secretion, which will cause menstruation not to come. Oral emergency contraceptive pills, which cause endocrine disorders, cause dysfunction of the body, and for women, menstrual disorders and amenorrhea are the most direct manifestations. There are many reasons why women don’t get their periods, so you should ensure that you get enough sleep, don’t drink and stay up late, and have a regular work schedule to avoid menstrual disorders.