The Five Stages of Western Fertility

A simplified demographic history

Written by Arctotherium.

Human net fertility is complicated.¹ Some things that matter on the margin are: winning elections, baby simulators in health class, war, housing costs, religion (both type and intensity), women’s education, population density, racial diversity, STD-induced infertility, baby bonuses, anti-natal propaganda campaigns and sterilizations, and status-messaging in soap operas. The full list is much longer. But most of these factors are just not that important—a few percent here, a few percent there, and with sharply diminishing returns.

Cross-cultural explanations are generally not that useful either; abuse of them is how you get bad ideas like the women’s liberation U-curve for fertility. Trying to explain the ups and downs of fertility across all of humanity with one model is a mistake. There are huge cross-cultural differences, and something that might matter a lot in one context (say, acceptance of infanticide among Christians versus Pagans in ancient Rome) might be irrelevant in another (say, 20th century East Asia).

Longitudinal analysis, which looks at a given society over time, is more instructive. And rather than look at the whole world (which is too diverse for coherent lessons) or a single country (which will be semi-randomly affected by particular legal regimes or events) it makes sense to look at a civilization. And what better civilization than the West, which is both extremely important and better documented than any other?

What’s more, Western norms heavily influence the rest of the world. If other countries imitating Western low fertility norms is the primary cause of global fertility collapse, as Lyman Stone claims, figuring out where Western low fertility norms came from is important! Fortunately, the history of modern Western fertility² is fairly coherent. There are local ups and downs and country-specific factors, but history as a whole can be split into five clear stages – as shown below.

Stage 1: The Western European Marriage Pattern

This stage is characterised by replacement level net fertility in Malthusian Europe, and far above-replacement fertility in the Americas and in Europe post-Industrial Revolution. The proximate causes are the Catholic Church-endorsed marriage pattern, and the post-Black Death importance of geographically-free wage labor. See my article ‘The Western European Marriage Pattern: Definition, Significance, and Misconceptions’.

The elements of the Western European Marriage Pattern that are relevant in the present context are as follows, though they are not the only elements.³

1. Absolute monogamy, with high standards of premarital chastity and fidelity, including very little divorce.⁴ Fertility was almost synonymous with marital fertility. The percentage of births outside of wedlock was in the single digits⁵ (and with child mortality approaching 50%, illegitimate children without paternal investment did not have good odds of survival). Cuckoldry rates were in the range of 1-2%.

2. Almost no family planning within marriage. Marital TFRs⁶ in early modern Western Europe approach the human biological maximum. Family sizes were controlled by delaying marriage or by not marrying at all, rather than by abortion, infanticide, contraception or other techniques to reduce fertility within marriage. This is not the preindustrial norm (marital TFRs in contemporary China and Japan⁷ were around 5). It is a consequence of the Catholic Church condemning family planning as a sin and the major Protestant denominations (initially) retaining that view.

   

   The Hutterites, an extremely natalist Anabaptist group, are often used as a model of maximum human fertility. Not only did married Western European women approach their fertility before 1790, but the age pattern also provides evidence against family planning: the ratio of births between married women in various countries and the Hutterites is approximately the same in each age band. If active family planning were at play, you would expect this ratio to fall in the older age bands, as couples stop having children after reaching their desired family size. Source: A Farewell to Alms by Gregory Clark.

3. Neolocality. Couples were expected to wait until they were economically self-sufficient enough to form an independent household before marrying, rather than to rely on their parents (this went both ways—parents were much less reliant on their children in old age than in most premodern societies). Marriage was therefore earlier and more frequent when economic conditions were good (the extreme case being the early American colonies), and later and less frequent when conditions were bad (the extreme case being after the Irish Potato Famine). In the Malthusian world before the Industrial Revolution, this served as a natural check on population growth, smoothing out the famine-induced boom-bust population cycles typical of agrarian societies. It was the late and infrequent marriage in bad times (which were only too common in the preindustrial world) that led to demographer John Hajnal discovering and describing this marriage pattern. However, late and infrequent marriage is a second-order consequence of neolocality, not a foundational part of the Western European Marriage Pattern.

The most relevant element is neolocality. This meant not only near-zero long-run population growth in the Malthusian era, but also comparatively few massive famines or other depopulation events (very useful for social stability and the preservation of capital and records). And when the Americas and Industrial Revolution arrived, rising incomes led to skyrocketing nuptiality, which led to a massive population boom and temporary European demographic supremacy.

Average age of first marriage in British parishes. You can see it fall by several years, especially outside of agricultural parishes, over the course of the first Industrial Revolution. This is because of rising incomes. Source: A Farewell to Alms.

Some readers may be surprised by this, because the Industrial Revolution is often blamed for falling fertility. In actual fact, the Industrial Revolution, by raising living standards and especially male wages, reduced the average age of marriage and thereby increased fertility. The demographic explosion this caused is what made the “First Industrial Revolution” so revolutionary, leading to centuries of Anglo-American cultural and geopolitical dominance.

The English economy sextupled from 1700 to 1860, but most of this was from the population nearly quadrupling (despite significant emigration to Ireland and America). Income per person increased, but nowhere near as much as after the second Industrial Revolution. Source: A Farewell to Alms.

Stage 2: The First Demographic Transition

This stage is characterised by a rapid fall in fertility from far above replacement to below, driven by falling marital fertility. The proximate cause is the moral normalization of family planning. See my article ‘Mind Viruses: In Defense of an Analogy’.

The first demographic transition began in France around 1760 and was greatly accelerated by the French Revolution, before spreading culturally to the rest of Francophone Europe.⁸ In the Anglosphere, it began about a century later with the Bradlaugh-Besant trial of 1877.⁹ The Nordic transition happened around the same time as that of the Anglosphere, and the German transition around 1900. Even more than the first-order effects of the Industrial Revolution itself, the timing of the first demographic transition determined the relative strengths of the great Western European powers of the 19th century

English and French TFRs over time. The Industrial Revolution-induced English population boom and France’s early transition are clear, as is the Bradlaugh-Besant trial of 1877. France had around three times the population of England in 1800. Source.

The proximate cause of the first demographic transition was the addition of family planning to the Western European marriage pattern. This greatly reduced marital fertility, such that even though nuptiality¹⁰ didn’t fall much and childlessness actually decreased, total fertility plummeted. In France, the moral normalization of family planning came from secularization and ignoring the Catholic Church. In Protestant Europe, the normalization of family planning was closely linked to Malthusianism and Darwinism, with state churches falling in line with broader cultural currents.

Nuptiality measured as number of women aged 15-50 married per thousand (left) versus fertility measured as TFR (right) in Europe across subnational units in 1900. You can see massive fertility variation between France (transition began around 1760), England (transition began 1877), and Germany/Italy (transition about to begin). This does NOT correspond to massive nuptiality differences. Sources for left and right.

To some extent, this was inevitable: zero family planning with early marriage and collapsing infant mortality leads to massive family sizes¹¹, which most people who are not part of extremely natalist religious groups (like the Israeli Haredim) are not willing to deal with. But the timing was highly contingent. The French fertility transition began a century before the mortality transition; the two were more or less contemporaneous in the Anglosphere; and the fertility transition lagged the mortality transition in the Germanosphere, with historic consequences. A difference of a generation or three matters.

The relevant number here is period NRR (meaning net reproductive ratio). NRR is similar to TFR, but measures the number of daughters per woman. NRR < 1 means below replacement. Of the listed countries, only the Netherlands, Italy and Spain were above replacement in 1930. The US, Canada and Australia also dipped below replacement around this time, though they were slightly higher than Britain. Source.

Western fertility reached a local nadir around 1930, with most countries solidly below replacement.¹² At the time, demographers believed this was permanent, and writers such as Oswald Spengler prophesied inevitable population aging and Western decline before the rising tide of color. They were wrong.

Stage 3: The Baby Boom

This stage is characterised by a rapid rise in fertility to well above replacement, driven by increasing nuptiality. The proximate cause is the rise in young men’s relative wages and status beginning in the 1930s, leading to earlier and more frequent marriage. See my article ‘The Baby Boom: Lessons and Patterns’.

The Baby Boom was primarily a marriage boom, caused by a sharp rise in young men’s wages and social status¹³, both in absolute terms and relative to their female counterparts. Western fertility went from well below replacement to well above it, though the exact magnitude of the Boom varied from one country to another.¹⁴

Source.

The Baby Boom is so important because it occurred during a time of extremely rapid technological advancement, urbanization, rising incomes and education (for both men and women, though faster for men), and falling mortality. Every Western country near or below replacement in the 1930s was clearly above it by 1960.

With illegitimacy still in the single digits, the boom can be reduced to two things. More marriage (nuptiality) and higher marital fertility. In every Boom country except for France, the United States and Austria, higher nuptiality explains 85% or more of the Baby Boom.

Rising nuptiality explains 123% of the Baby Boom in the median Boom country, since marital fertility actually collapsed in many of them, especially the “fringe-Western” countries still undergoing the First Demographic Transition. Source.

What caused this dramatic rise in marriage? It turns out that it can be entirely explained by a sharp rise in young men’s relative wages and status, as compared to the young women they sought to marry.

Average male vs female wages over time. Note how closely the ratio (grey dotted line) corresponds to the Baby Boom. This actually understates things, because the ratio was particularly strong for young people. Older women entered the workforce during WWII and remained there, and young men’s wages have stagnated more than any other group’s since 1970. Source.

As in the case of the First Demographic Transition, contemporary demographers thought this state of affairs might continue indefinitely.

US population projection from 1966 versus actual US population trajectory. The actual trajectory matches the lowest projection, but this masks a huge compositional difference. Projection D assumed TFR would slowly drop to 2.4 and net migration would remain at 400,000 per year, whereas the US actually had below-replacement fertility and much higher net migration. Source.

Stage 4: The Second Demographic Transition

This stage is characterised by a rapid collapse from significantly above replacement to well below replacement fertility, and a shift from marital to non-marital fertility. The proximate cause is second-wave feminism and the sexual revolution making marriage less useful (leading to lower marital fertility) and therefore less appealing (leading to lower nuptiality). See my article ‘Human Reproduction as Prisoner’s Dilemma’.

Unlike the first demographic transition, which began decades apart in different Western cultures¹⁵ and took generations to unfold, the second demographic transition was extremely coordinated across countries. Within a span of six years, the United States (1973), France (1975), Germany (1970), Britain (1973), and the Nordics (1969) all went from being poised for a never-ending population explosion, of the sort that gave Paul Ehrlich nightmares, to our current path of population aging and demographic decline. This is downstream of the cultural and political homogenization of the West, which itself is downstream of better communications technology and post-WW2 American hegemony.

Core-Western France, Germany, Sweden, and Britain all went from significantly above replacement in 1965 to below by 1975. The US, not shown here, went below replacement in 1973. Fringe-Western Italy (with its backwards southern half) and Spain (out of political synchronization thanks to Franco) have a similar pattern but Spain is delayed by a decade. Source.

The proximate cause of the second demographic transition is the enormous suite of changes that fall under the rubric of second-wave feminism and the sexual revolution. Some of the most important include:

1. Unilateral and no-fault divorce. Not only does this reduce marriage rates and increase divorce rates (lowering nuptiality), but the lack of security also encourages spouses to invest more in themselves (via education or career) and less in specialization of labor or relationship capital, including children, because said investments can be zeroed out at any time (lowering marital fertility).

2. Affirmative action, informal education and career preferences for women, along with a welfare state that carried out large and direct impersonal wealth transfers from men to women outside of marriage. This greatly reduces the appeal of marriage for women, and effectively put the mechanism behind the Baby Boom into reverse.

3. The moral delegitimization of marriage. Just as the First Demographic Transition was driven by the moral legitimization of family planning, the second was driven by the delegitimization of marriage. The institution that legitimized sex and children in the eyes of both society and the law becomes just one lifestyle among many. This might seem like an advance in freedom, but the main effect was to misalign people’s short-term incentives and long-term interests. The vast majority of people prefer to raise children within a stable, two-parent relationship. By inverting the sexual incentive to marry (as chastity is not expected outside of marriage¹⁶ but fidelity is expected within it) and removing the legal privileges of children born within wedlock, the short-term incentives no longer push people to marry. This makes it much harder for them as parents in the long run.

As far back as we have records, British illegitimacy never exceeded 10% until 1980. Now it is 55%. Source.

The First Demographic Transition was driven by falling marital fertility, and the Baby Boom by rising nuptiality. The second demographic transition was driven by both falling marital fertility and falling nuptiality.

After the initial collapse, several Western countries (Denmark, Finland, Sweden, Belgium, France, the Netherlands, and the United Kingdom, plus the Anglosphere¹⁷) saw significant rises (>0.3) in TFRs from their local nadirs over the next few decades. The Germanosphere saw a much smaller rise.

Regional European fertility, 1960-2010. Note that the decline is not monotonic. Source.

The reason this happened is a timing effect: some of the initial TFR collapse came from women delaying fertility. For biological reasons, fertility can only be delayed so far, and when the pace at which women delayed fertility inevitably began to drop, TFR rebounded slightly.¹⁸ Period fertility kept changing during this time, but cohort fertility was relatively stable.

Is the marginally higher Western TFR of 2000 vs 1970 significant? When discussing the long-term outlook of a population, yes, because it’s the TFR that matters. But when discussing individual behavior, cohort fertility is often the more relevant measure (because couples target a certain family size even if they start later).

Spain

Spain provides a test case of my arguments. By putting the boot on communist-adjacent New Left feminists, Franco froze in place Western norms around sexuality and marriage for a decade longer than they persisted in the core West. As expected, the post-Baby-Boom collapse was delayed a decade in Spain.

Some people claim that Francoist Spain’s fertility is a triumph of authoritarianism. I think this is mostly wrong, since the Baby Boom has the same source in almost every Western country. (There’s not much of a visible Boom because Spain was still going through its First Demographic Transition, so rather than a TFR rise there’s simply a stalled decline at a high level.) Source.

Contraception and abortion

Astute readers may notice that I haven’t mentioned the Pill or legalized abortion. This might seem strange. Isn’t cheap, effective, and convenient contraception the obvious explanation for the Second Demographic Transition? Why bother appealing to difficult-to-quantify cultural and legal changes when there’s such a clear technological answer?

The reason is simple: family planning is not a difficult problem. Even without the most common premodern solutions of abortion and infanticide (which were taken off the table by Christianity), Western countries were able to reduce fertility to well below replacement in the interwar period using the same techniques that have been available since people first figured out where babies come from. Even if these techniques are unreliable and inconvenient at an individual level, they are more than sufficient at the population level.

There is the more sophisticated argument that the Pill caused the sexual revolution by enabling casual sex with minimal risk of pregnancy. Pre-pill methods of family planning require some level of foresight and typically the cooperation of both partners (and are therefore difficult to use outside of long-term stable relationships such as marriage), while using hormonal birth control is trivial and can be used unilaterally by women without male input.

In this version of the model, it’s not that modern contraception caused fertility collapse. Instead, modern contraception changed social norms to devalue long-term fidelity, and that’s what caused fertility collapse. This is more plausible, but still wrong.

The legal and social changes did not require technological backing. The Soviet Union went through most of them in the 1920s, legalizing unilateral divorce, homosexuality, and abortion, and giving illegitimate children the same status as those born in wedlock. The extreme backwardness of rural Soviet society meant that these changes primarily affected the major urban centers. By the mid-1920s, more than half of Moscow marriages ended in divorce and abortions outnumbered births 3:1 – 60 years before the US reached a comparable state. These changes were partially reversed by Stalin, who was concerned about the need for Soviet society to remain strong and populous in the face of the German threat.¹⁹

Japan

There is no Western country that went through the sexual revolution and second wave feminism without legalizing contraception, but Japan’s legal system and many of its social norms were forcibly aligned to the West after its defeat and conquest in the Pacific War. Like other fringe-Western cultures that had not yet gone through the First Demographic Transition (Spain, Portugal, Italy, Quebec), it experienced a partial Baby Boom, driven, like the true Baby Booms elsewhere, by increasing nuptiality. And as in the core West, it experienced both second-wave feminism and a sexual revolution, with the corresponding fertility drop to well below replacement. Unlike in the core West, the Pill was not legalized until 1999.

Japanese fertility across centuries. As usual, take premodern fertility estimates with a grain of salt, though Japan is more reliable than most. You can clearly see the Meiji Restoration (which led to absolute monogamy in Japan) and the imposition of gender equality by the United States (1947) on this chart, but that’s not the important part. Notice how fertility clearly takes another dive around 1970, when Japan was going through similar social changes as the West, but notably not in 1999, when the Pill was legalized. Source.

Japan gives us an opportunity to check whether the technology or the social and legal revolution were more important. If the Pill were the main driver of the Second Demographic Transition, either directly or by allowing for new social dynamics, we would expect little to no drop around 1970 and a clear drop in 1999. We actually see the opposite.

Stage 5: Recent collapse

This stage is characterised by a fall from slightly below replacement-level to far below replacement-level fertility, driven by the young and the low-IQ. The proximate cause is smartphones and the internet leading to less unprotected sex, plus rising age at marriage hitting biological walls.

After several decades of approximate stability at slightly below replacement, fertility fell sharply in most Western countries starting around 2012 (though the timing varies by country). Since 2015²⁰, the US TFR has dropped by 0.22, Canada’s by 0.35, the UK’s by 0.32, Australia’s by 0.33, New Zealand’s by 0.50, Norway’s by 0.27, Denmark’s by 0.25, Sweden’s by 0.43, the Netherlands’ by 0.23, Germany’s by 0.14, Belgium’s by 0.26, Switzerland’s by 0.25 and France’s by 0.33.

I’ve chosen to use Birth Gauge’s table rather than a line chart because a lot of this decline is very recent and official sources are often out of date or based on projections rather than measurements. Source. Here’s a line chart.

This decline might look small compared to the previous wild swings, maybe too small to count as a separate stage, but it’s coming after decades of near-stability or slight rises. Most demographers did not see it coming, with the exception of a handful who thought carefully about the interaction of fertility-age curves and delayed marriage. But even they mostly missed the proximate cause.²¹

This chart is the change in age-specific fertility rates since 2006 in the United States. You can see that the decline is overwhelmingly due to mothers in their twenties. This is partly a function of later and less frequent marriage, and partly a function of singles having less unprotected sex. Source.

The most important thing to grasp about the recent Western fertility collapse is that it is concentrated among the lower classes, the unmarried, the young (below 30), the uneducated, and recent non-Western immigrants. In other words, fertility is collapsing among the low-IQ and low impulse control.

Birth rates by subgroup in the United States, 1990–2020. Notice the stability of married and educated fertility. The concentration of the fall in the unmarried, the uneducated and Mexicans is clear. Source.

Why? In part, Charles Murray’s observation in Coming Apart that marriage was shifting from a society-wide institution to an upper-class one²² is finally having the demographic impacts you would expect. Very few people²³ want to raise kids alone or with a rotating series of unrelated partners, and modern contraception is convenient enough that almost anyone can use it. The rest is opportunity cost.

The big change around 2012, as with the Great Awokening, is the rise of the Internet, smartphones and dating apps. Specifically, the opportunity cost for doing anything is much higher than before, because we always have the zero-marginal-cost, frictionless option of having fun online. It’s not the opportunity cost of children that matters here; marital fertility remains high and stable. It’s the opportunity cost of sex and, relatedly, finding a husband or wife. Putting it crudely: rather than have unprotected sex or even dating seriously, teenagers and young adults are going online instead. There are more and more singles, and singles are having fewer and fewer kids.

I list this as the final stage of the Western fertility story (for now), but the exact same phenomenon is occurring in Latin America and is responsible for the sharp collapse of Latin American fertility since about 2012.

Conclusions

If there’s one big takeaway from all of this, it’s that very few people saw any of these changes coming before they happened. It can be easy for pronatalists interested in demography to engage in doom-mongering about the strong negative trends of the past half-century, but things can and have changed fast in both directions. The future is malleable.

Left: my schema as applied to the Netherlands (recall the difference between net and gross fertility when looking at pre-WWII TFR data). Source. Right: my schema as an infographic.

Arctotherium is an anonymous writer interested in demographics and the future of civilization. You can find more of his writings at his blog Not With A Bang or at his Twitter.

---

Support Aporia with a paid subscription:

You can also follow us on Twitter.

1. I specify “net” because falling infant and child mortality is easily the single biggest thing that affects TFR. But this doesn’t much matter if family sizes remain constant.

2. When I say “Western,” I mainly mean the Anglosphere, the Germanosphere, France, the Low Countries and the Nordics. These countries all got wealthy early and displayed the Western European Marriage Pattern, low kinship intensity and high levels of achievement. All of these countries are culturally, genetically and historically similar. Italy, Iberia, and Quebec are all fringe-Western, being comparatively backwards both economically and socially until after WWII, before converging with the “core West” in the 20th century. Japan is not Western, but has a similar history (early industrialization, US side of the Cold War) and its convergence with Western social and legal norms as a result of WWII makes it a useful comparison.

3. See The WEIRDest People in The World by Joseph Heinrich for a book-length treatment.

4. This is one of the big differences between Imperial Japan and the pre-60s West. Western divorce rates were low and required some level of fault. Imperial Japan, on the other hand, had the highest divorce rate in the world. However, divorce was almost entirely a prerogative of the husband, reflecting very different set of incentives from those created by post-60s divorce law and family courts.

5. With the (amusing) exception of a brief period in the 19th century when a number of German states banned marriage among the poor to reduce the strain on public resources. But the exception proves the rule: even under these conditions, illegitimacy only reached 14% at the highest.

6. The TFR is calculated by constructing an imaginary woman who experiences the age-specific fertility of women in a given population between the ages of 15 and 49 at a certain point in time. You can think of this as constructing a woman who experiences the life cycle fertility typical of her population in a single year.

Marital TFR is calculated by constructing an imaginary woman who experiences the age-specific fertility of MARRIED women in a given population between the ages of 15 and 49 at a certain point in time. A marital TFR of 8.6 does NOT mean that the average married couple has 8.6 children, because very few women get married at 15 and remain married through age 49. The vast majority of married women marry later, don’t remain married through their reproductive years, or both.

For similar reasons, the TFR inflates the fertility of premodern societies because significant numbers of women died between the ages of 15 and 49.

7. Source is A Farewell to Alms, page 73.

8. Quebec, culturally isolated from France by British rule, and culturally isolated from the Anglosphere by the French language and deliberate insularity, managed to avoid the First Demographic Transition altogether.

9. I’ve seen some wrong interpretations of this paper circulate on Twitter/X, so here’s where I point out that the main effect of the Bradlaugh-Besant trial was to morally normalize family planning, not provide contraceptive techniques or technologies (the techniques in the relevant pamphlet being largely ineffective). See the Bradlaugh-Besant section of ‘Mind Viruses: In Defense of an Analogy’ or read the paper itself for details.

10. Nuptiality just means the frequency and characteristics of marriage within a population. A common measure is the fraction of women aged 15-50 married, ranging from 0-1. Earlier, more frequent, and more stable marriages can all increase nuptiality.

11. The extreme example of this is Mexico in the 1960s, which had a net (not gross) TFR of 6, comparable to ultra-Orthodox Jews today, for the entire country. This is why 1960s Mexico, with very little immigration, dominates the list of most rapidly growing countries in history.

12. I’ve seen claims that the post-WW1 loss of Western cultural self-confidence, or First Wave feminism, which reached its apogee in those years, are responsible for Western fertility dipping as low as it did. These factors probably did matter, but I think these are very clearly secondary to the First Demographic Transition, which was comes down to family planning. Maybe Western fertility would have remained above replacement in the 1930s without early feminism or WW1, but there still would’ve been a phase-change from the default Western European Marriage Pattern.

13. From the memoirs of Hungarian physicist Eugene Wigner (via Gwern):

Once I asked my father, “Why are people so attached to money?” He responded simply, “Because of the power and influence it gives them.” I disliked this bit of cynicism and told him so. It was years before I saw that he was largely right: The human desires for power and influence are very deep and strong. I learned a great deal from my father which I failed to fully credit at the time. These talks with my father led me to wonder, “Why am I on this earth? What do I want to achieve?” I felt my purpose should be to marry, to begin my own family, and to provide this family with a proper home and nourishment. Today, these things come far more easily and many youths no longer know what to strive for. Many of them see power and influence as the only valid goal. But in 1919, providing a home and nourishment was a valid purpose.

14. The US and France were somewhat anomalous in that they saw big increases in marital fertility in addition to rising nuptiality.

15. I use “cultures” and not “countries” intentionally. The first demographic transition was more cultural than legal.

16. Of course, this was always somewhat honored-in-the-breach. In 1953 in Italy, about a sixth of brides were pregnant at the time of marriage (Castiglioni and Zuanna 1994). But these exceptions prove the rule: pre-sexual revolution, having sex served as an incentive to quickly marry, with long-term benefits to both individual and society.

17. The US saw a bigger rise, reaching replacement in 2007, because of the massive Hispanic (mostly Mexican) Baby Boom triggered by the 1986 IRCA. (Hispanics in 2008 had a TFR of 2.9, with Mexican-Americans at 3.1). But other recent immigrant diasporas are going to follow different patterns, and the Financial Crisis ended Mexican-American fertility exceptionalism, so this doesn’t change the broad Western picture. Something similar is happening with Arab and African immigrants in France. Both US whites and ethnic French were on the high side of Western fertility during this period and remain so to this day, but not by nearly as much as national TFRs would suggest.

18. For a more thorough explanation of this phenomenon, see ‘Demographic explanation for the recent rise in European fertility’ by Bongaarts and Sobotka. The same phenomenon is at work in the post-90s Eastern Bloc fertility rebound.

19. The USSR then went through another sexual revolution in the 1960s, again without much modern contraception (abortion being the contraceptive method of choice).

20. 2015 was chosen because that’s where Birth Gauge’s numbers start. The decline begins a few years earlier.

21. A fun game is comparing MacroTrends numbers, which use UN population projections from a few years ago, with actual up-to-date numbers from Birth Gauge. With the exception of Afghanistan, where the Taliban takeover seems to have stalled the decline, MacroTrends numbers are uniformly too high.

22. In part because the welfare state replaces most of the economic functions of marriage for the lower classes, and in part because “no fault divorce plus family court hell plus low impulse control and high time preference” is a really terrible combination. Society no longer tries to make marriages work; it does its best to incentivize breaking them up instead. Maintaining a stable marriage is now the sole responsibility of husband and wife, which raises the bar for making it work, a lot. In the long run, people follow incentives.

23. When writing about fertility or marriage I make a deliberate effort to use gendered terms (men, women, husband, wife), because this is the area where sex differences are most important. Here I use “people” rather than “women” intentionally. Too much fertility discussion focuses exclusively on women and women’s incentives and desires, to the exclusion of men.