How To Increase the Total Fertility Rate

and if we don't

TFR in developed countries is now well below replacement; if it stays there the native born population will decline. Countries can prevent population decline for a while by immigration but global TFR is only a little above the replacement rate and declining;¹ if current patterns hold, world population will start going down sometime in this century, population in the developed world probably sooner.

Fifty or sixty years ago, when the risks of overpopulation played the same role in public discourse that the risks of global warming play today, a future of declining populations would have been considered good news. The predicted crisis did not happen; the populations of poor countries continued to grow but instead of getting poorer and hungrier as predicted they got richer and less hungry. The orthodoxy has reversed, declining population is now widely regarded as bad news, a threat to, among other things, there being enough young people to support an aging population.

How might that threat be dealt with? Are there ways to reverse the decline in TFR? If not, what are the consequences?

The first question is why it happened. There are several possible answers, each of which implies a different approach to the problem. Here are three.

What Changed?

Figure 1

Figure 2

Figures 1 and 2 show a large part of what happened. From 1960 to 2020, median age of first marriage in the US increased by about 8 years, average age of mother at the birth of her first child by about 5 years. Women are getting married later and, married or not, having children later.

Figure 3

Figure 3 shows the connection to TFR; the marital childbearing window was reduced from about 18 years to about 10, the years lost being most of the most fertile. By 2020 the median woman got married only about three years before her fertility began to decline, twelve years before it dropped to almost nothing.

Why?

The Manosphere Explanation

One explanation I have seen online blames it on the differing tastes of the sexes, men wanting to sleep with as many women as possible, women with the highest status man who will have them. The result: Most women are uninterested in most men, target a small minority of the highest status.² The high status men take the opportunity to sleep with multiple women, may or may not eventually marry one of them. When the women get too old to be worth seducing they give up on the hope of marrying a high status man and find a lower status man to marry — with the best part of their childbearing years over. The lower status men spend their twenties involuntarily celibate because the women of about their ages are all chasing the high status men, with luck marry in their thirties a woman also in her thirties.

There are two different ways of interpreting this story. In one the women are acting rationally, prefer to spend their twenties having casual sex with high status men with one chance in ten or twenty that one of them will eventually marry them. In the other the women badly overestimate their chance of marrying the men they sleep with, would prefer earlier marriage if they knew the real odds

Career vs Kids Explanation

In most past societies, the main career of most women was bearing and rearing children and running a household. One reason was that, with premodern mortality rates, maintaining a country’s population required something close to nonstop child bearing. A second reason was that physical strength was required for most alternative careers and men are, on average, stronger than women. A third was that men and women like sex, sex, absent reliable contraception, produces children, and producing and rearing children gets in the way of other careers.

Modern medicine has very nearly eliminated child mortality. Technological progress in recent centuries has largely replaced muscle power with machinery. Modern contraception backstopped by legal abortion has made it possible to separate sex from child bearing. The result is to make careers other than wife a practical option for most women. The more attractive, higher status, better paid careers mostly require extensive training, go better, especially in their early stages, if not punctuated by interruptions for bearing and rearing children, so pursuing a career is a reason to marry later, start child bearing later or not at all, have fewer children.³

Here again, there are two possible ways to interpret the story. In one the women are acting in their rational self-interest, taking advantage of the opportunity to live a life that is, for most, better than a life focused on household and children. In the other the women are making a mistake, led by unrealistically rosy pictures of the one option, unrealistically gloomy pictures of the other, to make what is, for most, the wrong choice.

Pessimism Explanation

Birth rates go up in good times, down in bad. At least part of the reason is that producing and rearing children is harder when you are poor than when you are rich, another part that bringing children into the world seems a better idea the better the world you expect them to live in. The first makes birth rates depend on views of the near future, the second of the further future.

In objective terms, the world today is substantially better than the world of fifty or a hundred years ago, lower mortality rates, higher real incomes. Subjectively, many people view the present as worse, the future as much worse. The popular basis for gloom in the developed world in the last few decades has been climate change; some couples argue that it is wrong to bring children into a world on the verge of collapse. Now for some it is artificial intelligence.

How Can it be Changed?

For each of the three, the answer depends on whether people are correctly acting in their individual self-interest. If they are, changing what they are doing so as to raise fertility rates requires changing the facts that motivate them, a different solution for each of the three explanations.

For the first explanation, that means either making short-term relationships less attractive, perhaps by banning contraception and abortion, difficult to do or enforce in a modern society, perhaps by changing norms to restore the traditional idea that non-marital sex is shameful, also difficult short of a widespread religious change, or to make long-term relationships more attractive. Suggestions for doing that range from subsidizing child rearing to legal changes around marriage to make it more attractive, with changes some view as positive, such as criminalizing adultery or making the terms of divorce less favorable to women, viewed by others as negative.

For the second, the facts could be changed by making the career of housewife more attractive, other careers less, perhaps by changes in tax law that disfavor two income households. They might also be changed by reducing the costs of combining career and motherhood. For both the first and the second, a technological fix might be to develop ways of extending fertility, giving women more years in which to bear. Present approaches, freezing eggs and/or using host mothers, are a very small step in that direction. Some way of slowing the changes that reduce fertility with age, perhaps by slowing aging, would be a considerably larger one.

For the third, changing the facts means making the future more attractive, a desirable change we have other reasons for — if we knew how to do it.

If the problem is that women (or men) misperceive the situation, the solution is to produce and spread better information. Bryan Caplan attempted to do it with the book Selfish Reasons to Have More Kids, which argues that the costs of rearing children are less, the benefits more, than most couples believe. My contribution is offering arguments and evidence that climate change is very unlikely to be catastrophic, may not be on net negative. Other people can attempt it in other ways. One problem with that as a way of raising TFR — not my motive nor, so far as I know, Caplan’s — is that the perception that an author has incentives to convince you of something other than that he believes it is true is a reason not to be convinced.

If TFR Continues To Fall

One possible solution to the problems posed by falling populations is to replace human workers with robots, more generally for technological change to reduce the need of the old for the young, perhaps by making medical care less expensive. Another is to slow aging or at least its effects.

So far my argument has been put in terms of averages, but people differ in ways relevant to fertility; some subpopulations, such as Amish or Haredi, have TFR well above replacement. If populations decline, an increasing fraction will be descendants of philoprogenitive groups. One conservative of my acquaintance argues that conservatives have higher birth rates than liberals, looks forward to a future when his opponents have bred themselves out of existence.

If the characteristics that lead to higher fertility rates are highly heritable, whether for genetic or cultural reasons, the result will be to push TFR, and eventually population, back up. If not, both may continue to fall, with the effect of selective reproduction balanced by selective conversion, religious, cultural, or political, in the other direction.

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1. By some estimates global TFR is already below replacement.

2. Here “status” is defined by whatever characteristics attract women, probably different for different subpopulations.

3. To the extent that this is true only of the more attractive career the effect should be disgenic due to abler women having fewer children.