Know your cycle

The menstrual
cycle explained

About once a month, your ovaries produce an egg along with hormones such as progesterone and oestrogen.1

If you have sex around the time of ovulation (when the egg is released), a sperm can fertilise the egg before it moves to the womb (uterus).1

Oestrogen and progesterone work to prepare the lining of your womb (called the endometrium) for pregnancy. It thickens as it gets ready for the fertilised egg to implant and grow.1

If the egg is not fertilised or if it doesn’t implant, the lining of your womb breaks down. This is called menstruation – also known as a period – and typically lasts about 4-8 days.2

In addition to oestrogen, hormones such as follicle stimulating hormone (FSH) and luteinizing hormone (LH) are produced so that a new egg can be released from the ovaries … and the whole cycle starts again.1

diagram of a period being counted on a calendar

What are
hormones?

Hormones are chemical messengers produced by a special group of cells called endocrine glands.3 They are produced naturally in the body and travel in your bloodstream until they reach their receptor.3 The hormone then produces a cascade of cellular effects which leads to the regulation of lots of different processes – from growth and metabolism to sleep and, as we’ve already covered, your reproductive cycle!3,4

As already mentioned, progesterone and oestrogen are the key players when it comes to reproductive health, and specifically during the menstrual cycle, lining the womb and preparing it for pregnancy.1

diagram of hormones

References

  1. NIH. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan. Available at: https://www.ncbi.nlm.nih.gov/books/NBK537132/ Last accessed May 2025

  2. NHS Inform. Periods (menstruation). Available at: https://www.nhsinform.scot/healthy-living/womens-health/girls-and-young-women-puberty-to-around-25/periods-and-menstrual-health/periods-menstruation Last accessed May 2025

  3. Stárka L, Dušková M. What is a hormone? Physiol Res. 2020 Sep 30;69(Suppl 2):S183-S185

  4. Lateef OM, Akintubosun MO. Sleep and Reproductive Health. J Circadian Rhythms. 2020 Mar 23;18:1

Skip to toolbar