How the Menstrual Cycle Works

It goes without saying that every menstruating woman knows what is happening to her body once a month for most of her adult life… or does it? If you are nodding along but know deep down you feel like you could know more, this blog is for you. Here is how the menstrual cycle works.

For many of us, have our first period around age 11-14 and do that every month unless we’re pregnant or begin menopause around age 50. But there’s so much more to it than that and I truly believe that understanding female hormones empowers women to take their health and their happiness into their own hands. I’m pretty passionate about this – can you tell?

Now, there’s certainly no shame in not knowing the details. In fact, I would gamble that most women don’t know  how the menstrual cycle works. So, let’s go over the basics, shall we?

How Do Estrogen and Progesterone Affect The Body?

Estrogen and progesterone are the main female sex hormones. Estrogen is predominantly responsible for the physical changes that turn girls into women: the growth of breasts and pubic hair and the beginning of the menstrual cycle. Your ovaries are the main point of the production of estrogen, with the adrenal glands and fat tissue acting as some secondary points of production. Estrogen moves throughout your body affecting nearly every tissue, including your brain, bones, heart, skin, and more. Estrogen is higher during days 1-14 of your cycle.

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Produced mainly in the ovaries and the adrenal glands (and the placenta when pregnant), progesterone is known as the more “calming” hormone of the two. Progesterone “counters” the effects of estrogen in the body, reducing anxiety, increasing sleepiness, helping to build and maintain bone, and promoting appetite and fat storage, among other things. Progesterone ramps up and is higher during days 15-28 of your cycle.

Both estrogen and progesterone help to regulate the menstrual cycle.

What Are The Different Phases of The Menstrual Cycle?

Your menstrual cycle is defined by the first day of bleeding (day 1) and lasts until the first day of your next period. Cycles are highly individualized and there is quite a range of what can be considered “normal,” but the average cycle is about 28 days.

On day 1 of your cycle, both estrogen and progesterone are low, which signals the pituitary gland (a pea-sized gland at the base of the brain) to release Follicle-stimulating hormone (FSH). FSH stimulates the ovaries to form a follicle in preparation for ovulation.

Ovulation is the part of the cycle where a mature follicle (part of the ovary) discharges an egg. It’s during this time that the egg travels down the fallopian tube and either implants in the endometrium (uterine lining) if fertilized by sperm or slowly dissolved and passed out of the body, along with the uterine lining during your menses.

The follicle produces more estrogen to prepare the uterus for pregnancy. For around days 12-14 of the cycle, estrogen peaks and triggers the release of luteinizing hormone (LH). This LH surge causes ovulation.

The ruptured follicle, now called the corpus luteum releases progesterone and estrogen to prepare for pregnancy. If pregnancy occurs, estrogen and progesterone stay high throughout, a phenomenon commonly mimicked with most hormonal birth controls. If pregnancy does not occur, estrogen and progesterone drop and menses occurs.

What Are The Effects of Estrogen Dominance?

Estrogen dominance is where estrogen is higher than progesterone. Some of the side effects include:

    • Fibrocystic breasts
    • Weight gain
    • Heavy or irregular menses
    • Mood swings

Read more in our guide to Estrogen Dominance.

What Are The Effects of Low Progesterone?

    • Irritability/ emotional
    • Breast tenderness
    • Clots in menstrual blood
    • Short periods
    • Anxiety
    • Depression
    • Insomnia
    • Inability to maintain a pregnancy

Read more now about how to boost Progesterone.

We can’t talk about the menstrual cycle without covering birth control. Luckily, I’ve done that. In depth. 

Read more:
Birth Control and What Your Doctor Didn't Tell You
The Effects of Using Birth Control for PCOS
Birth Control and The Medical Gender Bias

Download your FREE Hormone Starter Kit with 7 Day Meal Plan & Recipe Guide Book. This package is designed to get your hormones back on track!

If you're interested in learning even more about the natural rhythm of your body and hormones, then I'd like to invite you to read more about Fertility Awareness Method.

YOU are ultimately in control of your body and your hormones. 

If you're looking for help in understanding how to get bring your hormones back into balance, check out how to work with me and my incredible team. We offer consults in Portland, Oakland, and Virtually. Learn More Here. 

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About The Author


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Dr. Jolene Brighten is a Functional Medicine Naturopathic Medical Doctor and the founder of Rubus Health, a women’s medicine clinic that specializes in women's hormones. She is recognized as a leading expert in Post-Birth Control Syndrome and the long-term side effects associated with hormonal contraceptives. Dr. Brighten is the best selling author, speaker and regular contributor to several online publications including MindBodyGreen. She is a medical advisor for one of the first data-driven apps to offer women personalized birth control recommendations.Read more about me.