Why are global birth rates falling? Part 3

Welcome to the third and final part of the post series where I explore the reasons behind the sharp change in birth rates currently happening everywhere around the world. Have you already read Parts 1 and 2? If so, then let’s pick up where we left off.

How low will it go?

Let’s recall that the global average fertility rate has halved from around 5 children per woman in the 1950s to around 2 in 2021. In OECD countries, it was only 1.5 in 2022. Currently, over half of countries in the world have a fertility rate (FR) below the population replacement level of 2.1. How much further is it going to decline?

Well, recently a benchmark Global Burden of Disease (GBD) study was published in the medical journal Lancet. This study used existing data from 1950 to 2021 to estimate future fertility rates worldwide.

The paper forecasts that by 2050, 155 out of 204 countries will have a fertility rate lower than the replacement rate, and by 2100, this number will grow to 198 countries. By 2100, the global average FR is estimated to be only 1.6 children per woman, with just six countries expected to have enough children to maintain their populations: Chad, Niger and Somalia in Africa, the Pacific islands of Samoa and Tonga, and Tajikistan.

Now the GBD study used reference data up to the year 2021 and estimated that fertility rates would eventually stabilize between 1.25 and 1.5 in most advanced countries by the year 2100. However, by 2023, many countries are already well below that range. South Korea’s fertility rate for 2100 was estimated to average 0.82 (with a forecasted range of 0.73 to 0.92), but it was already at 0.72 in 2023. Similarly, the GBD study estimated that in Latin America, the average fertility rate would reach 1.3 by the middle of this century. Yet in 2023, many of those countries, including Uruguay, Costa Rica, Chile, Jamaica, and Cuba, already have a FR around 1.3 children per woman. The changes seem to be happening much faster than theoretical models predicted. More accurate estimates will likely be produced in the future as the most recent fertility data becomes available to researchers. But I am getting the feeling that whatever is happening is not following any logical statistical models or past trends.

Regarding how low fertility rates will go, some influencing factors can only continue up to a certain point. For example, the average age of first birth for women in OECD countries has steadily increased from 28.6 in 2000 to 30.9 in 2022. While it may continue to rise for a while, there is a limit. Science cannot extend menopause. Although technologies exist that allow women to freeze their eggs and thus postpone the maximum age of giving birth, these procedures are still costly and not widely available. 

However, other factors are indefinite. If social, economic and environmental conditions continue to deteriorate, and anxiety and uncertainty about the future persist, more and more people will postpone having children. There is a caveat here, though. Those currently choosing to wait may still have children later in life if conditions improve. Therefore, this sudden drop in births around the world may be a temporary dip, and the fertility rate may still stabilize around the 1.5 mark, halting further decline.

But even if and when fertility rates stabilize, the global population will continue to shrink as long as the FR is below the replacement rate. During my lifetime, the global population has grown from 5 billion to 8 billion. However, recent projections suggest that the next billion will only be reached around 2040. I was actually surprised to learn that the peak in global live births was already reached in the 2010s, and the number has been steadily declining since 2018. While the UN predicts that the global population will peak at around 10.4 billion in 2086, more conservative estimates (which consider recent trends in declining fertility) suggest that we may not even reach 10 billion before the population starts to shrink around the middle of this century. Given that the most recent GBD study overestimated the extent to which fertility rates may decline, the change in global population dynamics could arrive even sooner.

Is it really that bad if global populations decrease?

Is it really that bad if there are less people in the world, I hear you ask? You would think only good things will come from the situation where only wanted, loved, and cared-for children are born into the world. Well, it depends on how you look at it. My guess is, it will probably get worse before it gets better.

High-income countries will be fine initially. For some time now, their populations have been sustained by immigrants. Places like the US, Canada, the UK, and New Zealand are all experiencing record low birth rates and record high immigration, actually resulting in population increases. But how long can this last? With global populations falling, there will soon be fierce competition over who can attract more immigrants. Either a nation becomes extinct or, more likely, it becomes assimilated with other populations through immigration or emigration.

Fewer children being born means a larger percentage of the population is elderly, placing greater pressure on the younger generation to maintain the workforce and take care of the older generation. There will also be increased demand for pensions and health services for the elderly, along with decreased tax revenue and a shrinking workforce. However, I believe societies can adapt to this with technology, given enough time. We are already hyper-productive as a society, and maybe it is a blessing in disguise that our economy, which is built on the premise of unstoppable growth, eventually has to stop and reconsider. Instead of focusing on continuous growth, it will need to prioritize maintaining a good quality of life for everyone.

The main question in my mind is how fast these changes will occur. It might be useful to illustrate the effects of a low FR with a simple mathematical exercise. Let’s say you have a total fertility rate of 1 child per woman and a population of 1000 people equally divided between men and women. With a FR of 1, 500 women will have 500 children (assuming these are also equally distributed between boys and girls). In the next generation, the number of women is significantly smaller (only 250). These women will give birth to 250 children, half of whom will be girls. So in the third generation, there are only 125 potential mothers. By the fourth one, this number has halved again. This doesn’t even take into account the unequal division of males vs. females or those children who don’t survive to adulthood. The population will just gradually shrink over time, generation by generation. The lower the FR, the faster this will happen.

If this trend continues perpetually, humanity would eventually go extinct. It would take a long, long time because there are more than 8 billion of us, but mathematically speaking, that would be the outcome.

I think before we ever get to that point, society will have changed so much that we might not recognize it anymore. A permanent reduction in birth rates will definitely come with its own share of positive changes. Education can be more affordable and effective with fewer pupils per teacher, increasing the quality. We could certainly benefit from having more well-educated people on the planet. Government policies will likely become more supportive of working mothers, including paid parental leave for both parents, and societal shifts towards a more equal share of parenting and household duties, allowing mothers to balance their careers and the ideal number of children they may want to have. Land and homes will probably also be cheaper due to less demand from shrinking populations. Fewer people mean fewer resources need to be extracted and processed, reducing pollution and stress on the environment.

Shrinking populations may actually bring people and families closer together. We might return to extended families where several generations live together, with grandparents helping to take care of the grandchildren. This support can allow parents to balance their work and personal lives without making as many sacrifices to have children. Our descendants may actually have a better life than we do (assuming we don’t irreversibly screw up the ecosystem or start World War III).

So for now, I will stop thinking about global birth rates falling. Nothing I can do about it anyway. And even if I could, I now feel better about the fact that maybe this isn’t a bad thing after all.

But I will still be reading the headlines tomorrow morning as well.

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** I am acutely aware of the fact that I did not have time to write about the potential connection between microplastics and infertility because I have been putting this post together for literal weeks now. But I promise I will come back to this topic soon so I can stop having recurring nightmares of a post-apocalyptic wasteland where the last remnants of humanity fight for survival (or maybe it was just a Mad Max movie and not a dream, I’m not entirely sure, because I’m at that age now where sometimes I fall asleep before I finish watching a movie. Hey, it’s not easy being in your late 30s!).