Are pro-natalists living on the same planet ?

World population is almost certain to rise over the 21st century (unless we blow ourselves up)

Jun 19, 2025

Pro-natalism (the idea that people should have more babies than they choose to do at present) has become an established orthodoxy,[1]. The central claim is that, unless something changes soon, human populations both global and national, are going to decline rapidly, with a lot of negative consequences. This is simply not true, on any plausible assumptions about fertility[2]

There’s no need for me to do any calculations here. For many decades he Population Division of the UN Department of Economic and Social Affairs has been producing population projections for the world, and individual countries, under a variety of scenarios. One finding is unambiguous. Short of a drastic decline in fertility, there will be more people on Earth at the end of this century than there were at the beginning

The range of projections considered plausible is the shaded area. All the projections in that range show population increasing for several decades to come, and remaining higher than at present at the end of the century. The reason is simple. Global fertility is close to the replacement level (one surviving daughter per woman) at present, but past growth means that a large proportion of the population is in, or approaching, child-bearing years. It’s only when this group ages out that the effects of declining fertility, assumed in the lower projections will start to dominate

What about the blue dotted lines? These assume drastic reductions in fertility. On the low side, that involves the entire world becoming like South Korea, where the combination of high employment rates for women and pre-modern male attitudes on gender role has produced reproduction rates below 0.5.

But even in this extreme case, world population in 2100 only falls to 6 billion, the same as in 2000. I was around at the time, and did not feel as if there were too few people about.

One reason these predictions have only a limited range of variation is that most of the growth in population is already baked in. There are 2 billion or so children under 14 at present in the world, and most of them will be around in 2100 as will their soon to be born siblings.

What about the need for workers? One unsatisfactory feature of long-running projections like this is the use of outdated statistical concepts such as the “dependency ratio”, that is, the ratio of people aged 15-64 to everyone else. That made sense 50 years ago, when this range represented the period between leaving school and retiring in most industrial societies. But these days (and it will be even more so in 2100) education continues well past 20 and retirement is often deferred to 70 or more. A look at the age group 25-69 shows that it is going to remain more or less stable in absolute numbers declinging only marginally relative to the growing population

Population projections for individual countries depend largely on what happens to migration. In the absence of stringent restrictions, the flow of migrants from poorer to richer countries will largely offset differences in fertility, meaning that the trajectory for individual countries will look similar to that for the world.

Of course, if you combine low fertility and an already-old population with hostility to immigrants , and you can’t stop your own young people from seeking a better life abroad, you end up with a sharply declining population, as in South Korea and Hungary. But it’s much easier to let more migrants in (there are plenty of young adults, many of them well-educated, knocking at the door) than to persuade people to have more babies.

There is no difficulty in gaining access to these projections, and anyone with a spreadsheet and a bit of time can reproduce them. Yet I’ve read dozens of pro-natalist articles in both traditional and new media and the evidence is never mentioned. Maybe I’m living on the wrong planet.

John Quiggin's Blogstack

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