Understanding the menstrual cycle

Understanding the menstrual cycle

Have you ever wondered why you feel energetic one week and in need of rest the next, why your skin sometimes changes, your focus feels different or your mood shifts without a clear reason. That is not a coincidence. That is your menstrual cycle at work.

What is the menstrual cycle exactly

The menstrual cycle is the recurring process in which the body allows an egg to mature, builds up the lining of the uterus and sheds it again when no fertilization occurs. This does not happen randomly but follows a clear biological rhythm controlled by hormones. The main hormones involved are estrogen, progesterone, FSH and LH. These hormones work together and ensure that the right processes happen at the right time.

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1.Menstrual phase

During this phase, the uterine lining that was built up in the previous cycle is shed.This is menstruation. The body makes a fresh start.

More information about the Menstrual phase
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2.Follicular phase

After menstruation, the building phase begins. FSH stimulates several follicles inthe ovaries that contain egg cells. One follicle becomes dominant. At the sametime, estrogen levels rise, causing the uterine lining to thicken again inpreparation for possible implantation.

More information about the follicular phase
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3.Ovulation

When estrogen levels become high enough, this triggers a surge in LH. This LH surgecauses the mature egg to be released from the ovary. This moment is calledovulation. The egg can be fertilized for about 12 to 24 hours after release. This is the most fertile period of the cycle.

More information about the Ovulation
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4.Luteal phase

After ovulation, the empty follicle becomes the corpus luteum. This structureproduces progesterone. Progesterone ensures that the uterine lining remainssuitable for a possible pregnancy. If fertilization does not occur,progesterone levels fall and menstruation begins again.

More information about the Luteal phase

Sources and references

Cleveland Clinic, Menstrual Cycle
https://my.clevelandclinic.org/health/articles/10132-menstrual-cycle

Office on Women’s Health, U.S. Department of Health and Human Services, Menstrual Cycle https://www.womenshealth.gov/menstrual-cycle

NHS, Periods
https://www.nhs.uk/conditions/periods/

NHS, Fertility in the menstrual cycle
https://www.nhs.uk/conditions/periods/fertility-in-the-menstrual-cycle/

Nillni, Y. I. et al. (2021). The Impact of the Menstrual Cycle and Underlying Hormones in Anxiety and PTSD. PubMed Central, PMC8819663.
https://pmc.ncbi.nlm.nih.gov/articles/PMC8819663/