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

Menstruation usually occurs when the thickness of the endometrium reaches 8-12 mm. The cyclic thickening and shedding of the endometrium is a key process in the formation of menstruation, and its thickness changes are regulated by hormone levels.

During the menstrual cycle, as follicles develop, estrogen levels gradually increase, prompting endometrial hyperplasia starting from 1-2 mm after menstruation. After ovulation, the corpus luteum forms and secretes progesterone, further thickening the intima to the secretory phase state, with richer blood vessels and glands. When the corpus luteum degenerates and hormone levels drop, the thickened endometrium loses support and sloughs off and bleeds, forming menstruation. This process requires the endometrium to reach sufficient thickness to be completed. Clinical observations show that the endometrium thickness is in the range of 8-12 mm when most women have menstruation. There may be differences among individuals. Some women may also experience menstruation at around 6 mm, while abnormal thickening of more than 15 mm may indicate endometrial disease.

If low menstrual flow or insufficient endometrial thickness occurs for a long time, it may be related to polycystic ovary syndrome, thyroid dysfunction or intrauterine adhesions. On the contrary, incomplete menstruation accompanied by excessive endometrial thickening should alert you to endometrial polyps or hyperplasia. It is recommended that those with menstrual abnormalities monitor endometrial changes through ultrasound and, if necessary, evaluate ovarian function in combination with sex hormone testing.

Maintaining a regular schedule and a balanced diet can help maintain normal hormone secretion and prevent excessive dieting or obesity from affecting endometrium growth. Foods rich in vitamin E and omega-3 fatty acids, such as nuts and deep-sea fish, may be beneficial to endometrium health. When menstrual cycle disorders or abnormal bleeding occur, you should seek medical treatment promptly to avoid taking hormone drugs on your own that may interfere with the normal cycle of the endometrium.