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How does a 'normal' menstrual cycle work?

Updated: Dec 2, 2023

hormones in the menstrual cycle

This is a very brief and simple overview of the menstrual cycle and the hormones which are involved. I think it is important to understand these terms, because often if you have any problems with your periods the terminology can appear confusing.

Plus, as something which happens monthly. I believe our education should be much better on periods and the menstrual cycle.

The five predominant hormones involved in the menstrual cycle are:

  • GnRH - located in the hypothalamus of the brain and stimulates the production of FSH and LH by the anterior pituitary gland.

  • FSH - Follicle-Stimulating Hormone produced in the anterior pituitary gland and stimulates the growth of ovarian follicles in the ovary before the release of an egg from one follicle at ovulation

  • LH - Luteinising Hormone produced in the anterior pituitary gland and causes ovaries to release an egg during ovulation. if fertilisation occurs, LH will stimulate the corpus luteum, which produces progesterone to sustain the pregnancy.

  • Oestrogen - produced in the ovaries and stimulated by FSH and responsible for promoting fleshiness of the tissues of the vagina and labia major/minor. It also makes cervical mucus receptive to sperm and prepares the endometrium for implantation. As oestrogen levels rise, FSH falls. Once oestrogen reaches a certain level, LH is activated.

  • Progesterone - produced in the ovaries and stimulated by LH. Progesterone is responsible for maintaining pregnancy and finishes preparation of the endometrium for implantation.

So how does this look, during the cycle of menstruation? The following would be considered a 'normal' cycle BUT what even is normal nowadays.

Day 1 - 13 is the follicular phase

During this phase, FSH is secreted by the anterior pituitary gland and stimulates ovarian follicles to produce and release oestrogen.

As oestrogen levels rise it inhibits FSH secretion.

Once oestrogen levels have reached a certain level it stimulates the anterior pituitary gland to start secreting LH.

This positive feedback stimulates LH which causes the dominant follicle to ovulate.

follicular phase

Day 14 is ovulation

During ovulation, an egg is released from the dominant follicle. Following the release of the egg, the follicle seals itself off and forms the corpus luteum. The corpus luteum helps produce progesterone during early pregnancy.


Day 15 - 28 is the luteal phase

During this phase, LH stimulates an increase in progesterone. As progesterone increases it prepares the endometrial lining and inhibits the secretion of LH & FSH.

But if fertilisation doesn't occur the corpus luteum degenerates causing oestrogen and progesterone to decline and the endometrium is discarded.

As progesterone and oestrogen are low they cannot inhibit the anterior pituitary gland and the cycle begins again.

luteal phase

Your body is an amazing thing. All these elements happen without us knowing. Unless of course problems start to occur.

I hope you have found this breakdown helpful.

Did you know in acupuncture a 'normal' period would have:

  • no (or very mild) pain

  • a regular cycle of 28 days

  • 5 days of bleeding

  • it wouldn't be too heavy or light

If you would like help with tracking your periods, please feel free to download this period tracker which I have created for you.

And please always get in touch if you have any other questions.

Love your fave acupuncturist


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