Are We Entering a Global Fertility Crisis?

Is it possible to be healthy on a sick planet?

Dr. Louise Rix
8 min readApr 6, 2022
Timo Volz on Unsplash

Inspiration for this post came partly from the book Count Down by Dr. Shanna Swan. Buy it here or listen on Audible here.

I wrote some months ago on why ‘Hormone Health’ is going to become the next major market in FemTech. However it became apparent to me as I was doing more research that I had captured part of the story without seeing how it fed into a wider and more worrisome picture. That is of a potential global decline in human fertility.

Declining Fertility Rate

During the 20th century, populations of industrialised countries all over the world have experienced a decline in Total Fertility Rates and many countries are now below the replacement level as seen in the chart below:

Skakkebaek et al. 2015. Pysiol Rev. Link

While discussing a decline in fertility we need to keep clear in our minds the difference between Total Fertility Rate (TFR) and human fecundity. TFR is the average number of children that would be born to a woman over her lifetime. This is influenced by socioeconomic and behavioural factors such as rising income, education, female labour participation, access to contraception and many others, as well as the rate of infertility.

Human fecundity on the other hand is defined as the biologic capacity of males and females for reproduction irrespective of pregnancy intentions. (Buck Louis, 2011). Or put another way, the maximum reproductive potential of a population.

Often the declining fertility rate is ascribed to socioeconomic and behavioural factors alone, rather than a decline in fecundity. As fecundity has no direct measure surprisingly little is known about how this has changed over time.

A decreasing TFR will have significant societal and economic impacts. In fact, even Elon Musk tweeted the declining birth rate was “…one of the biggest risks to civilization…”.

The focus on TFR shouldn’t blind us to a number of worrying health trends that point to an overall reduction in reproductive potential that may be contributing and are significant in their own right.

Ubiquitous Endocrine Disruptors

“There is not one person or animal on earth — from a polar bear in the Arctic, to a tree frog in the tropical rainforest, to a new-born child anywhere — that has not been exposed to man-made industrial or agricultural chemicals.” WWF

One potential cause of a decline in fertility is the ubiquitous presence of endocrine disruptors in our environment. Reproduction is regulated by hormones and is susceptible to the effects of exposure to endocrine disrupting chemicals (EDCs). The definition of EDCs is chemical compounds that interfere with the normal functioning of the endocrine system and the reproductive and other biological processes regulated by it.

There has been an enormous increase in the production of different types of chemicals during the last several decades throughout the world. Of the thousands of manufactured chemicals, it is estimated that 1000 may have endocrine-acting properties. Common EDCs include BPAs (bisphenol A) and phthalates, found in everyday products such as plastic food containers and personal care products and cosmetics. Another common EDC found in household cleaning products and industrial chemicals is polychlorinated biphenyls (PCBs). Yet more EDCs are used in or on the food we eat, such as herbicides, pesticides and fungicides applied to fruit and vegetables, such as glyphosate and vinclozolin. (1).

As consumers, we assume that the chemicals in our products or product packaging are safe for us. However, unfortunately this isn’t always the case. For example, the beauty brand Highr excluded the use of 1500 commonly used ingredients from their formulation after proprietary research found these to be potentially harmful. Another study found that babies fed with (plastic) bottles for formula had a 115% higher BPA level than those that hadn’t been given formula using plastic bottles (2). BPA is a ‘substance of very high concern’ because it is ‘toxic for reproduction’ (3). It is worth noting BPA-free plastics are often replaced with another BP-something, such as BPS, BPF, BPAF, BPZ, BPP, BHPF. Try using glass, ceramic or metal containers instead of plastic.

Hormone Health & Fertility

So how does this related to ‘Hormone Health’? As we’ve discussed, reproduction is regulated by hormones and a disruption in the finely balanced endocrine system by EDCs may result in a range of potential problems.

In Females

In females, EDCs have been linked to subfertility, infertility, improper hormone production, menstrual cycle abnormalities, anovulation and early decline in fertility (4).

Some possible mechanisms for abnormal hormone balance include certain pesticides which have been associated with reduced sex steroid hormone production and early menopause and a chemical called nonylphenol which has been shown to disrupt ovarian sex steroid hormone production and paraben exposure which was associated with decreased serum sex steroid hormone levels and decreased fecundity in females (4). Unfortunately the list goes on.

There is also evolving research that suggests EDCs may play a role in the seemingly overwhelming burden of hormone-associated diseases which are linked with lower fertility in females. However, more research is needed before any firm conclusions can be drawn.

Polycystic Ovary Syndrome (PCOS) — PCOS is the most common cause of infertility in females. It can be associated with abnormally high testosterone levels and high oestrogen. One study estimated 21% of females will now go on to develop PCOS (5). PCOS has been tied to high levels of BPA in numerous studies including one that stated BPAs may play a ‘major role’ in PCOS. (6, 7, 8, 9)

Endometriosis — Endometriosis is promoted by high levels of oestrogen and the prevalence is currently estimated at 10–15% of females of reproductive age (10). PCBs, phthalates, dioxins (all found in certain foods we eat) have all been implicated. One study in the The European Journal of Public Health said the link was ‘likely’ (11).

Other oestrogen dominant conditions — Uterine fibroids and other oestrogen dominant conditions are also extremely common. Uterine fibroids now being estimated in the UK at 10% (although for some sources and some populations this is much higher). Fibroids have been linked to PCBs, phthalates and dioxins (11).

In Males

Although my original article on Hormone Health focused on the effects on females, males are not immune. In males, EDCs have been linked by numerous studies to abnormal sperm counts, low testosterone levels and reproductive tract abnormalities however again more data is needed. Again these findings remain a contentious issue.

Low testosterone — Testosterone levels have decreased by 25% since 1999 according to one source (12). It is now thought up to 20% of males aged 15–39 years have testosterone deficiency. Low testosterone contributes to low sex drive and has a complex relationship with sperm production but likely lowers it. One study found a correlation between phthalate exposure and declining testosterone levels (13).

Erectile dysfunction (ED) — ED is on the rise. It is estimated that in 1995 there were over 152 million males worldwide who experienced ED. Projections for 2025 now show a prevalence of approximately 322 million, an increase of nearly 170 million males or a 110% rise (13).

Normal androgen levels are essential for erectile function and oestrogens also have an effect with high oestrogen levels being a risk factor for erectile dysfunction.

Drop in sperm count — Numerous studies have reported a drop in sperm count that is steep, significant and continuing. One study found that sperm counts in the west had plummeted 59% between 1973 and 2011 (14).

The table below shows the effects of multiple EDCs on semen parameters and male reproductive hormones:

Green et al. 2021. Environmental Research. Link

Where Does This Leave Us

According to an article in Nature, the rate of couples needing artificial reproductive technology is rising at 5–10% per year. Dr Swan also estimates that most couples will need fertility treatments to conceive by 2050. Unless there are significant changes then it is unlikely fertility clinics will be able to keep up with this demand.

What Should We Do About It?


If after reading this article you’re wondering how to reduce your exposure to EDCs. Here are some resources to get you started:

  • The Endocrine Society has a guide to reducing endocrine disruptors
  • The WWF also has a UK guide on avoiding endocrine disruptors
  • The Good Face Project has a guide on clean beauty
  • Scan your purchases with an app such as Impact Score for more information on chemical ingredients

As well as these resources, raising public awareness and adding public pressure to policy makers to clean up our environment can be useful. EDC Free Europe has more information on how you can take action.

Private Companies

The fertility sector is a booming category in FemTech and based on the predictions above will continue to grow rapidly. However, there is certainly a gap to be filled by private companies looking at solutions within Hormone Health including, or especially in, preventative care.

At a National Level

A multi-country monitoring system based on numerous proxies for human fecundity seems prudent, as well as greater regulation of potentially harmful chemicals and more funding into research in the space.

If you have thoughts or feedback I’d love to hear from you in the comments below. You can also reach out to me at

Important Notes

It is important to remember that correlation is not the same as causation and more research is needed, especially in females, in many of these areas. As already mentioned some of these areas remain contentious. For example one paper vehemently refuted the ‘Spermaggedon’ reported by Dr Swan.


  1. Endocrine disrupting chemicals: exposure, effects on human health, mechanism of action, models for testing and strategies for prevention
  2. Influence of Bottle-Feeding on Serum Bisphenol A Levels in Infants
  3. MSC unanimously agrees that Bisphenol A is an endocrine disruptor
  4. Exposure to endocrine disruptors during adulthood: consequences for female fertility
  5. The Prevalence of Polycystic Ovary Syndrome: A Brief Systematic Review — PMC
  6. Polycystic ovary syndrome: do endocrine disrupting chemicals play a role? — PMC
  7. The obesogen tributyltin induces features of polycystic ovary syndrome (PCOS): a review
  8. Endocrine disrupting chemical Bisphenol A and its potential effects on female health
  9. The Association Between Bisphenol A and Polycystic Ovarian Syndrome: A Case-Control Study
  10. Multigenerational endometriosis : consequence of fetal exposure to diethylstilbestrol ?
  11. Environmental Endocrine Disruptors and Endometriosis
  12. Testosterone levels show steady decrease among young US men
  13. The likely worldwide increase in erectile dysfunction between 1995 and 2025 and some possible policy consequences.
  14. Temporal trends in sperm count: a systematic review and meta-regression analysis | Human Reproduction Update | Oxford Academic



Dr. Louise Rix

Female Health, Product, ex-Chief Medical Officer at Béa Fertility, Founder, VC. 🧠 Writing about health tech, female health and The Mental Game 💡