Flat White

The fertility paradox – poverty vs prosperity

20 April 2022

12:00 PM

20 April 2022

12:00 PM

The world population had risen from 2.5 billion in 1950, to 6 billion in 2000, and now sits at over 8 billion leading to questions about sustainability.

Is this the real problem facing humanity rather than climate catastrophism? Fortunately, rising temperature and carbon dioxide levels have greened the planet and increased food production to feed the increased masses. The recent plan to use biomass as a fuel substitute, reducing available food and increasing its price, seems to have been sensibly forgotten.

With a predicted peak of 11 billion people by 2090, this one elephant in the room has become not just a talking point, but a whole herd of elephants. The majority of this population increase is occurring in Africa, with a population of 1.4 billion predicted to reach 3 billion by that date.

The inexorable rise in African population is inexplicably taking place against a background of regular famines, tropical diseases, AIDS and Covid, tribal conflicts, and other violence. Despite these problems, child mortality has fallen from 300 per 1000 in 1950, to 70 per 1000 in 2020. Fertility rates in some countries, such as Niger, remain as high as 7 children per woman, compared with low rates of 1 in Taiwan and Japan. Average figures are below replacement level at 1.5 in Europe and East Asia, 1.6 in Australia, 1.9 in the US (increased in Black and Hispanic populations and reduced in White Americans).

Part of the reason for this lower rate in developed countries is increasing infertility.

Before the contraceptive pill was popularised in the 1950s, the average worldwide birth rate was 5 children per woman, this has fallen overall to 2 per woman. Using the pill does not lead to subsequent prolonged infertility. One important factor that is increasing infertility in developed countries is delayed conception; female fertility starts declining from the twenties, with rapid decline after 35, while male fertility decreases after the forties. Overall 85 per cent of couples conceive in the first year of attempting pregnancy in America, 5 per cent in the second year, and 10 per cent have difficulty; the number experiencing difficulty is increasing. This compares with estimates of infertility of 2.6 per cent in Africa, with 18 years being the average age of first pregnancy.

China has a unique explanation for falling birth rates with its intentional One Child Policy; a further reduction in future population numbers is predicted as many female foetuses were aborted, meaning fewer potential mothers. This policy, started in 1980, was reversed in 2015, and resulted in an estimated 400 million fewer births. The epidemiological changes are already apparent, with a continually falling newborn rate and the proportion aged over 65 projected to increase from 9 per cent to 25 per cent. Its birth rate has been further adversely affected by high levels of atmospheric and water pollution, among the highest in the world; this has been associated with increasing levels of birth defects.

In the developed world, investigation reveals that 40 per cent of causes of infertility are due to female problems, 40 per cent male, and 20 per cent both.


Factors of significance include Polycystic Ovary Syndrome (PCOS) which is associated with obesity, hormonal changes, risks of diabetes, and high blood pressure. There may be other ovarian problems or physical abnormalities of the uterus such as fibroids or endometriosis. Sexually transmitted diseases (STD) such as chlamydia, gonorrhoea, syphilis, and AIDS can affect the ability to conceive or result in miscarriage. Low sperm count in the male may result from infection, a varicocele, even tight underpants have been incriminated. Figures from America suggest 20 per cent are due to PCOS, 17 per cent endometriosis, 17 per cent low sperm count, 12 per cent hormonal problems in either partner, 10 per cent uterine abnormality, 5 per cent varicocele, 3 per cent STD; in the rest no cause is found.

In the modern, sexually liberated era STDs are on the rise with a million new cases daily worldwide. Annual figures present a scary 130 million cases of chlamydia, 80 million gonorrhoea, 7 million syphilis, and 150 million cases of trichomoniasis. In Australia, annual case numbers in 2017 were 50,000 for chlamydia, 7,000 gonorrhoea, 600 syphilis, and 100 with HIV; these numbers have tripled in 10 years. These infections are more likely hidden in the female, resulting in long-term complications for infertility.

The incidence of PCOS is also on the rise. The condition was first diagnosed in 1935 and was considered rare. In recent years its incidence has been increasing, with surveys showing a rate of between 2 and 20 per cent. The underlying hormonal abnormality involves genetic and environmental factors, for example, it is more common in Hispanic women. 

Typical diagnostic features include a variable menstrual cycle, increased body hair, and obesity. Although obesity itself predisposes to infertility, only 50 per cent of PCOS sufferers are overweight. 

Studies have shown a reduced rate of conception in simple obesity, with 65 per cent achieving pregnancy compared with 80 per cent of non-obese, within a year of stopping contraception; it also reduces the success rate of IVF. As an increasing number of women in Western society become overweight or obese, this poses a significant risk factor; the proportion with ‘normal’ weight is predicted to decline from 50 per cent in 1990 to 30 per cent by 2030. 

The obesity problem affects male as well as female fertility. Figures suggest every 10kg of excess weight is associated with a 10 per cent reduction in fertility due to reduced sperm count; this can be reversed by weight reduction. A varicocele (collection of varicose veins on the testicle) is easily managed by surgical removal. There is some dispute about the effect of male underwear, but studies have shown men who wear tight-fitting underwear have sperm counts 17 per cent lower than those who wear boxer shorts.

At the other end of the spectrum, the incidence of malnutrition and underweight is increased in poor countries, such as in the African continent. This should result in lower pregnancy rates, increased miscarriage, low birth rate, smaller size, reduced intelligence, and later metabolic abnormalities. The paradox of fecundity is confirmed as studies show that chronic moderate malnutrition has only a minor effect on conception; interestingly also, the contraceptive effect of breastfeeding is of shorter duration, leading to an earlier subsequent pregnancy. 

Increasing child survival rates in poor countries like Africa relate to clean water programs, increased childhood vaccination, as well as food aid. The population growth relates to declining childhood mortality with falling, but still high, reproduction rates, starting at a younger female age.

The effect of environmental pollution in developed countries has become a point of concern. Apart from the known factors, such as smoking, alcohol and drugs, there are other chemicals known as endocrine-disrupting chemicals. These ECB’s include metals and chemicals in air, food, water, and beauty products and perhaps sunscreens (unknown), which can lower sperm counts and affect ovulation. These chemicals can be found in 95 per cent of the population of developed countries, with higher levels causing greater infertility.

Insecticide residue on fruit and vegetables has been shown to lower sperm counts as has mercury contamination of fish, and industrial pollution with other heavy metals; these contaminants have also been shown to reduce the success rate of IVF. A range of toxic metals, such as nickel, copper, lithium, and rare earths, are found in solar panels and batteries; currently there is no system for recycling these supposed renewables and the millions now time-expired are being dumped in tips, leading to inevitable leakage of toxins. DDT and polychlorinated biphenyls (PCB’s) were banned in the seventies, for the same reason, once absorbed these chemicals are slow to be removed and those born in the sixties and seventies had the highest lifetime exposure. Standard food preservatives, such as salt, sulphites, benzoates, and nitrites prevent food infection and make food safer, without known effect on fertility.

Concern is mounting about the possible testosterone-disrupting effects of phthalates from microplastics (MPs), average sperm counts have fallen 50 per cent in the last 50 years. 

These plastics are ubiquitous in the developed world, and impossible to avoid, should this fall continue it could result in complete male sterility in developed nations by 2045. These plastics can be found even in the placenta, with worrying implications for future generations. In an older pre-plastic Western era, like much of Africa, containers were made of wood, tin, pottery, glass, and paper, all of-necessity recycled.

Another area of concern relates to electromagnetic radiation from mobile phones; a 2020 review of animal and human studies did suggest reduced sperm count and sperm mobility. Other sources of irradiation include computers, wi-fi, TV, etc, mobile phones also have a direct heat-related effect on the testis when stored in a trouser pocket.

The paradox of high population growth in Africa and low population growth in the developed world has clear explanations; counter-intuitively, chronic mild malnutrition does not impair fertility. The explosion in Africa’s population relates to improved clean water supply, childhood immunisation with lower child mortality, and overseas food aid.

Around $50 billion annually is spent on aid for Africa, resulting in corruption and dependence, but with little effect on poverty. Aid needs to be directed to contraception and women’s education, with countries such as Nigeria and Kenya showing a clear link between educational attainment and birth rate. Unlike the developed world, the environment there is less chemically polluted.

The developed world has a created a problem for women resulting from overly delayed pregnancy for career enhancement, increasing obesity, reduced religious influence on multiple offspring, effective contraception, and increased STD. In the male, obesity is also a factor but there is increasing concern about environmental factors in the air, water, and food, affecting sperm counts and fertility. Studies have also shown that atmospheric pollution is associated with auto-immune diseases and depression. We need fewer people and a cleaner environment.

We are currently concerned about the effect of a colourless, odourless, atmospheric nutrient, when the real problem is the size of the population – there are worse problems in the atmosphere than CO2. Humanity has damaged the planet and is itself being damaged as a result, maybe with catastrophic outcome.

Dr Graham Pinn, FRCP, FRACP, FACTM, MRNZCGP, Retired Consultant Physician

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