NUNZIUM

Over the past 50 years, the world has witnessed a steep decline in fertility rates in virtually every country on Earth. The global fertility rate measures how many children per couple are born yearly. Worldwide, it changed from a value of 5 in 1951 to a value of 2.4 in 2022 - a decrease of more than 50%. While this measures the world average, it is worth noting that the fertility rate changes radically among different countries. While many African countries maintain high fertility rates, the countries driving the world's economy had 2022 fertility rates below the so-called "replacement threshold", which is the rate required to maintain the population - identified in a value of 2. For instance, the EU has a fertility rate of 1.6, with low peaks in Italy and Greece at about 1.3. China had 1.7, the US 1.8, all the way down to 1.4 and 1.1 for Japan and South Korea, respectively.

The main reasons for the decline are the social factors related to increasing prosperity. The most relevant aspect is access to high education, which delays the decision to conceive a baby for many couples. The social condition of women has improved drastically in the latest decades, which caused many to delay procreation to favour career development. Age is undoubtedly the most critical factor affecting a woman's fertility. While good health improves the chance of getting pregnant and having a healthy baby, it doesn't override the effects of age. A woman in her early to mid-20s has a 25–30% chance of getting pregnant every month. Fertility generally starts to reduce when a woman is in her early 30s and more so after age 35. By age 40, the chance of getting pregnant in any monthly cycle is only around 5%.

On top of this trend, it recently became clear that environmental and lifestyle factors also have an essential impact. Besides increasing obesity in the population, which is known to hinder procreation, a recent study published in Human Reproduction Update reported for the first time an analysis of the evolution of sperm quality. The result of the study indicates that, over the past 50 years, human sperm counts have fallen by more than 50% around the globe. If the findings are confirmed and the decline continues, it could have important implications for human reproduction. The review, and its conclusions, have sparked a debate among experts. Some say the findings are real and urgent, but others say the data do not convince them. However, more studies are being published to find possible explanations for this trend. For example, scientists observed the harmful effects of microplastics - already known to harm several lifeforms - on male reproduction and sperm quality. More scrutiny is also dedicated to the several chemicals employed throughout modern societies.

Arguably, many elements are driving our species into an infertility trap. If we are to avoid it, it is vital to adopt social, political, environmental and lifestyle changes to bring this situation under control. For the first time, a robust political signal was launched in this direction just a few days ago by Japan Prime Minister Fumio Kishida, who openly recognized the country's population crisis and its implications for Japan's economy. He said Japan was "on the brink of being unable to maintain social functions" due to the falling birth rate. In a policy address to lawmakers, Fumio Kishida said it was a case of solving the issue "now or never" and that it "simply cannot wait any longer. In thinking of the sustainability and inclusiveness of our nation's economy and society, we place child-rearing support as our most important policy". Kishida added that he wants the government to double its spending on child-related programs and that a new government agency would be set up in April to focus on the issue.