What could be the reason for suddenly missing periods without being pregnant?

For women of childbearing age, sudden absence of menstruation without pregnancy is likely caused by ovarian endocrine dysfunction. For example, conditions such as hyperprolactinemia, premature ovarian failure, or even polycystic ovary syndrome can lead to amenorrhea. In women over 45 years old, ovarian insufficiency may cause sudden amenorrhea and absence of pregnancy, leading to physiological menopause. Therefore, when a woman experiences sudden amenorrhea without pregnancy, she should go to the hospital for a color Doppler ultrasound to assess endometrial thickness, and then consider whether progesterone medication is needed to induce menstruation.