The Science of the Sanitary Pad

Figure 1 - Menstrual products - a menstruators’ best friend. Reprinted from Ref [1].

Period.

This word means different things to everyone. It can cause us to think of questions such as, have I started? Am I leaking? Should I change my pad/tampon? But it can also be something we love: it can be seen as a process that helps us stay healthy and happy. Anyone can join this conversation; periods are not just a women’s-only area!

But for all of us menstruators, we have one best friend when it’s our time of the month: our menstrual products (angelic noises). 

For the people who are reading this article and are hearing the words “period” and “menstrual products” for the first time, here is a debrief on what periods are. 

Periods begin at the age of around 10 to 16, whereby reproductive systems begin to prepare for pregnancy [2]. The menstrual cycle has 4 stages. The first stage is menstruation, also known as the period. 

During this stage, our bodies produce hormones - such as progesterone and oestrogen - which build the lining of our uterus. This prepares our bodies for a fertilised egg, and hence, pregnancy.  If the egg isn't fertilised, the uterus lining breaks down, and is released via the uterus [3].   

This stage consists of vaginal bleeding that lasts anywhere from 3-8 days (although it is normally in the range of 5-7 days). Normally, about 30-72ml of blood is lost during this time [4]. This menstrual fluid does not only include blood and a dead, dissolved egg cell, but it also includes endometrial lining, bacteria and secretions of the vagina and cervix. In short, this means menstruators release an egg each month, until menopause - a natural process, where someone no longer has a period and no longer has the ability to get pregnant naturally [2] - hits at around age 45 to 55 [5]. 

The second stage is the follicular stage. This stage occurs between the first day of your period until ovulation. During this process, a hormone called follicle-stimulating hormone (FSH) starts to rise. The eggs grow inside of follicles in the ovaries, and FSH informs the ovaries to prepare to release the egg. These follicles also produce oestrogen, which causes the lining of the uterus (also called the endometrium) to be built and grow thicker. This is a key function, as a thicker lining is used to support the growth of a fertilised egg [6].

Figure 2 - A menstrual cycle tracking app. Tracking your menstrual cycle can help a lot with understanding your menstrual cycle. Reprinted from Ref [9].

The third stage is ovulation. The increase in oestrogen during this process causes another hormone, called luteinising hormone (LH), to rise. This increase in LH causes an egg to be released from the ovaries. The egg then travels through the oviduct, towards the uterus. If fertilised by a sperm cell, the egg reaches the uterus, where it settles on top of the endometrium. Over 9 months, this grows into an embryo and then into a baby. If not fertilised, the egg dissolves into the endometrium and is shed during your period [7].

The final stage is the luteal phase. The luteal phase consists of an increase in progesterone from the follicles to prepare for a possible pregnancy. This stage occurs from the end of ovulation to the start of the next period. The follicle, which housed the released egg, turns into a corpus luteum (a group of cells that forms in the ovary). This corpus luteum then produces progesterone and oestrogen. If the egg was fertilised, the progesterone would help support the egg as it turns into an embryo during the early stages of pregnancy. If the egg is not fertilised, the corpus luteum starts to break down around 9-11 days after ovulation. This causes a drop in progesterone and estrogen, leading to menstruation [8].

These 4 stages then repeat in a cycle until menopause occurs. Each cycle lasts normally around a month, though it varies from person to person and other factors can affect this (e.g. PCOS or endometriosis). 

One more point to note is that periods are not exclusively a women-only function - some men get periods too. Periods are usually deemed as a ‘women’s-only process’, hindering men and other societal groups from also joining in the conversation. Periods should instead be referred to as a biological process, letting anyone join the period conversation.

Now, lets hop right back to our discussion on sanitary products! 

The most used menstrual product is the sanitary pad and, in my eyes, that makes complete sense. They are easy to use - all you do is unwrap and stick them on your underwear, they last for hours, you can wear them overnight, they can come with/without wings - the list goes on.  

But has anyone wondered why sanitary pads work so well? 

The first disposable sanitary pads were made from cotton and gauge in 1896, but due to material shortage, sanitary pads started using wood pulp as an absorbent material [9].

But the introduction of plastic changed everything! With this new material, sanitary pads were produced using SAP (super absorbent polymer). This is an absorbent material with leak-proof polypropylene or polyethylene as the ‘back-sheet’. This makes  the sanitary pad entirely  waterproof. This combination of SAP and either polypropylene or polyethylene creates the legendary product - the sanitary pad (super-heroine music) [9].

But whenever plastic is involved, there are usually repercussions. Pads, tampons and applicators have been polluting our seas and making landfills larger day-by-day. Over the course of a lifetime, a single menstruator could use somewhere between 5 thousand to 15 thousand pads and tampons, most of which end up as plastic waste in landfills [10]. The reason we use these products at this rate, is due to the fact that they’re convenient and easy to use. If you’re a first-time menstruator, pads are such a simple thing to use. Tampons also allow you to do certain activities like swimming, that you can’t do when wearing a pad. With that being said, reusable and sustainable menstrual products are seeing an increase in popularity, with people opting to switch to products such as cloth pads, period underwear and menstrual cups in recent years [10].

However, the stigma around periods prevents menstruators from embracing reusable period products to their fullest. People rarely talk about this topic in a casual setting, fearing the taboo associated with menstruation. The promotion and awareness of reusable menstrual products is also limited [10]. 

According to Chris Bobel (Professor of Women's, Gender, and Sexuality Studies in University of Massachusetts), “Breaking down the stigma around menstruation, is critical to moving toward a more socially and environmentally thoughtful future”. Only when people understand that periods are a bodily function that shouldn't be stigmatised, will people be able to crack down on the issue of period pollution [11].

Periods are a normal bodily function for over 800 million people in the world every day. Just because they are a process that affects women and some members of the LGBTQ+ community, does not mean they should be pushed aside as if they don’t exist. Periods are not something that should be shushed or hidden, instead they should be discussed and celebrated. The free discussion of periods would help so many people, even those who don't have periods! Free discussion allows people to educate themselves and provide help and aid for someone when they have issues related to their periods or sexual health in general. Openly discussing periods would alleviate so many troubles we currently face, helping us to achieve UN SDG 3: Good Health and Wellbeing. When periods and overall sexual health become an easier topic to talk about, promotion of sustainable menstrual products would also increase, also keeping us in line with UN SDG 12: Responsible Consumption and Production.

Only when this discussion is allowed, can we start cracking down on the problem of period pollution and also allow the promotion of sustainable menstrual products. 

Change will come, when the conversations change [11]!

References

[1] Alina Blumberg, “White and Red Floral Shoe,” Pexels, November 17, 2020. [Online]. Available: https://www.pexels.com/photo/white-and-red-floral-shoe-5907692/. [Accessed 27 February 2021].

[2] National Health Service, “Starting your periods - NHS,” NHS, August 5, 2019. [Online]. Available: https://www.nhs.uk/conditions/periods/starting-periods/. [Accessed 6 April 2021].

[3] BBC, “The menstrual cycle - Human reproduction - KS3 Biology Revision - BBC Bitesize,” BBC Bitesize, n.d. [Online]. Available: https://www.bbc.co.uk/bitesize/guides/z9fgr82/revision/3. [Accessed 6 April 2021].

[4] National Health Service, “Menopause - NHS,” NHS, August 29, 2018. [Online]. Available: https://www.nhs.uk/conditions/menopause/. [Accessed 27 February 2021].

[5] National Health Service, “Periods - NHS," NHS, August 5, 2019. [Online]. Available: https://www.nhs.uk/conditions/periods/. [Accessed 29 January 2021].

[6] Tampax® “Menstrual Cycle Phases | Tampax®,” Tampax®, n.d. [Online]. Available: https://tampax.com/en-us/period-health/menstrual-cycle-phases/. [Accessed 6 April 2021].

[7] Jennifer Walker and Dr Sarah Johnson, “What is Ovulation? The What, When and How - Clearblue,” ClearBlue, May 17, 2017. [Online]. Available: https://uk.clearblue.com/how-to-get-pregnant/what-is-ovulation. [Accessed 6 April 2021].

[8] Laurie Ray, DNP, “The Menstrual Cycle: Phases of Your Cycle,” HelloClue, December 11, 2018. [Online]. Available: https://helloclue.com/articles/cycle-a-z/the-menstrual-cycle-more-than-just-the-period. [Accessed 6 April 2021].

[9] C Technical, Pexels, January 12, 2012. [Online]. Available: https://www.pexels.com/photo/people-woman-hand-notebook-6473737/. [Accessed 6 April 2021].

[10] Anuradha Barman, S D Asagekar and Pooja Katkar, “An Overview On Sanitary Napkins,” TechnicalTextileNet, n.d. [Online]. Available: https://www.technicaltextile.net/articles/an-overview-on-sanitary-napkins-7850. [Accessed 10 December 2020].

[11] Alejandra Borunda “How tampons and pads became so unsustainable”, National Geographic, September 6, 2019. [Online]. Available: https://www.nationalgeographic.com/environment/2019/09/how-tampons-pads-became-unsustainable-story-of-plastic/. [Accessed 29 December 2020].