How thick does the endometrium need to be for menstruation to occur?

Generally, the endometrial thickness needs to reach 10-12mm before menstruation occurs. Detailed analysis is as follows:

Menstruation occurring when the endometrium reaches a thickness of 10mm may be related to aging. For example, in women approaching menopause, ovarian function gradually declines and estrogen secretion decreases, restricting endometrial proliferation. When hormonal fluctuations trigger shedding, the endometrial thickness often remains around 10mm. Additionally, if hormone levels are low—such as insufficient estrogen secretion or being in an earlier stage of transition from the proliferative to the secretory phase of the menstrual cycle—the endometrium may shed at around 10mm, leading to menstruation.

Menstruation occurring when the endometrium reaches a thickness of 12mm is commonly seen in women of reproductive age. During this phase, ovarian function is active and sufficient estrogen is secreted to adequately stimulate endometrial proliferation. If in a later stage of the secretory phase, the endometrium thickens significantly under continuous hormonal influence and often reaches approximately 12mm before shedding due to progesterone withdrawal, resulting in menstruation. Women with stable and balanced hormone levels may also experience menstruation when the endometrium reaches 12mm.

If repeated monitoring indicates a明显 abnormal relationship between endometrial thickness and the onset of menstruation, or if accompanied by excessive or scant menstrual flow, prolonged menstrual periods, or other issues, timely medical evaluation of hormone levels and endometrial condition is recommended. In daily life, maintaining a regular routine and avoiding excessive dieting or late nights can help maintain hormonal balance and ensure normal physiological changes of the endometrium.