Can You Have Your Period Today with 8mm Endometrial Lining Last Week?
Yes, you can absolutely have your period today if your endometrial lining was 8mm one week ago, as this thickness is well within the normal range for the late proliferative or secretory phase of the menstrual cycle in premenopausal women.
Understanding Endometrial Thickness in Premenopausal Women
Normal Cyclical Variation
- Endometrial thickness varies throughout the menstrual cycle due to hormonal fluctuations, and there is no validated absolute upper limit cutoff in premenopausal women 1, 2.
- The endometrium undergoes cyclical changes regulated by estrogen and progesterone, proliferating and regenerating during each menstrual cycle 3.
- An 8mm endometrial thickness is entirely normal during the reproductive years and can occur at various points in the cycle 4.
Why 8mm is Compatible with Menstruation
- In premenopausal women, endometrial thickness is NOT a reliable indicator of when menstruation will occur, as the timing depends on hormonal triggers rather than thickness alone 1.
- The endometrium can be 8mm or thicker in the late proliferative phase (just before ovulation) or in the secretory phase (after ovulation, before menstruation) 3, 5.
- One week is sufficient time for the hormonal cascade (progesterone withdrawal) to trigger menstrual bleeding, regardless of the measured thickness 4.
Key Clinical Context
Postmenopausal vs. Premenopausal Distinction
- The 8mm threshold has clinical significance only in postmenopausal women for cancer screening, not in premenopausal women for predicting menstruation 6, 1.
- In postmenopausal women, 8mm or greater warrants investigation for malignancy, but this does not apply to reproductive-age women 7, 8.
What Drives Menstruation
- Clinical symptoms and hormonal changes, rather than thickness measurements, determine when menstruation occurs in premenopausal women 1, 2.
- The withdrawal of progesterone support triggers endometrial shedding (menstruation), which can occur at various endometrial thicknesses 3.
Important Caveats
- Do not apply postmenopausal endometrial thickness thresholds to premenopausal women, as the physiology is fundamentally different 1.
- If you are experiencing abnormal bleeding patterns, heavy bleeding, or other concerning symptoms, evaluation should focus on structural abnormalities (polyps, fibroids, adenomyosis) rather than thickness alone 1.
- Endometrial thickness measurements in premenopausal women have limited diagnostic value for predicting menstruation timing 2.