Demographers project that the world population will decline for the first time in the second half of the century, if not sooner.
And the consequences are already being felt, especially in East Asia and Europe, where policymakers are attempting to reconcile the needs of an ageing population with the needs of young people.
Except in Sub-Saharan Africa, where families continue to have four or five children, the high-fertility trend is coming to an end everywhere else. More parents are delaying childbirth and having fewer babies as women receive access to education and contraceptives, and as the anxieties associated with having children continue to grow.
It may take decades for the transition to occur, but once it does, decline (like growth) spirals exponentially.
In 2019, South Korea's fertility rate hit a new low of 0.92, or less than one child per mother, making it the lowest in the developing world.
This low birthrate, along with rapid industrialisation, has driven the population out of rural areas and into suburbs. Although major cities like Seoul continue to expand, putting a strain on infrastructure and housing, schools in rural areas are often closed and abandoned due to a lack of children.
To boost the fertility rate, the government has handed out baby bonuses. It increased child allowances and medical subsidies for fertility treatments and pregnancy. Health officials have showered newborns with gifts. Hundreds of kindergartens and daycare centres are also being built. Pink seats are reserved for pregnant women on every bus and subway car in Seoul.
However, Deputy Prime Minister Hong Nam-ki acknowledged this month that the government had not made enough progress despite spending more than $178 billion over the last 15 years urging women to have more children.
Thousands of miles away, in Italy, the sentiment is familiar.
Capracotta, a small town in southern Italy, has seen its population decline sharply, from 5,000 to 800 inhabitants, who are now mostly residents of old homes.
A maternity ward in Agnone, about a half-hour away, closed a decade ago because it had less than 500 births per year, the national minimum to remain open. Six babies were born in Agnone this year.
Birth estimates fluctuate depending on how governments and families react, but according to projections published last year in The Lancet by an international team of scientists, 183 of the 195 countries and territories will have fertility rates below replacement level by 2100.
China's population is projected to plummet from 1.41 billion people today to about 730 million in 2100, according to their model.
According to census data released on Tuesday, China's rust belt in the northeast has lost 1.2 percent of its population in the last decade. Heilongjiang Province was the first in the country to run out of money in the pension fund in 2016. In Hegang, a province "ghost city" that has lost almost 10% of its population since 2010.
Many countries are starting to see that they must adapt rather than resist. Universities in South Korea are being pushed to combine. Municipalities have been merged as towns age and shrink in Japan, where adult diapers now outsell baby diapers. Some cities in Sweden have moved services from education to elder care. And elderly people are being forced to continue working nearly everywhere. Germany is considering raising the retirement age to 69, after recently raising it to 67.
Germany's birth rate recently rose to 1.54 from 1.3 in 2006, thanks to expanded access to quality child care and paid maternity leave.
Demographers caution against seeing demographic loss solely as a source of concern. Many women are choosing to have fewer children. Smaller populations result in higher incomes, more sustainable economies, lower carbon emissions, and a better quality of life for the fewer children born.
No nation with a significant slowdown in population growth has been able to boost its fertility rate well above Germany's minor increase. In shrinking economies, there is no evidence of income increases, and there is little guarantee that a reduced population means less environmental stress.