All About Endometrium:
Menstruation 101

Period.  Time of the month.  Aunt Flo. Crimson wave.  Shark week. The curse. A recent survey of 190 countries identified 5,000 euphemisms for monthly menstruation.  No matter how you say it, you have to admit that it is amazing how the female body renews and regenerates each month.  Although sometimes it can feel like a major inconvenience or a burden, women’s physical potential and resilience are indeed a powerful force.  On average, women experience menstruation for about 38 years. It pays to understand, appreciate, and celebrate menstruation in all of its phases.  Here’s a little refresher of the monthly process of menstruation. We highly recommended reading this to get a complete picture of your fantastic fertility functions.

Menstrual phase:  Shedding the endometrium

As the 90s pop song Closing Time goes, “Every new beginning comes from some other beginning’s end.”  Menstruation begins at the onset of bleeding, in tandem with the ovarian cycle, on the first day of each new cycle and lasts on average 3-5 days.  When the previous month’s egg is not fertilized, the uterine lining, or endometrium, is left unused and as a result, exits the body. The endometrium is a bi-layer system that attaches to the muscle walls within the uterus.  The inner endometrium is comprised of stem cells that work to repair and regenerate cells in the uterus while the outer layer detaches and sheds or supports pregnancy.

Proliferative phase:  Regeneration of the endometrium

A woman’s body wastes no time getting back to preparing for egg fertilization.  The proliferative phase prepares the uterine lining to house a fertilized egg with a nutrition-rich supply of blood and tissue.  At the same time, the ovaries are nurturing follicles to produce one mature egg for fertilization and manufactures more and more estrogen in preparation for ovulation.  The endometrium is lined with uterine glands that respond to estrogen by changing shape and becoming longer to increase blood flow. As a result, over the course of about 9 days, the endometrium increases up to three times its thickness and water content.  

Secretory phase:  Setting the stage

The secretory phase is aptly named because the endometrial glands produce a mixture of high carbohydrate glycogen secretions as a food source for a fertilized egg for about 13 days.  Once again the endometrial glands respond to increased progesterone manufactured by the corpus luteum in the ovaries with a change in shape that’s softer and more coiled. If fertilization is absent, progesterone levels diminish as the corpus luteum breaks down.  This results in a reduction of blood flow to the endometrial glands and the lack of circulation lead to cell death which is why the layer slips off during menstruation.

It never ceases to amaze how tiny cells respond to micrograms of hormones, and different organs communicate and work together every day in your body!  It’s an important reminder of all of womanhood’s capabilities, creativity, and strength. Next time you experience a twinge of premenstrual cramps think to yourself “Anything you can do, I can do bleeding”.