A newly published paper found pronatal policies only worked when supported by culture.

"Maternity benefits increased fertility only among women who grew up in religious families" in the Baltics.

This could explain why many pronatal policies have not boosted fertility more. 🧵.
In 1982, there was a big expansion in child benefits in Estonia, Latvia and Lithuania including maternity leave wage benefits, a cash payment for birth and 18 months of job protection.

Five East European countries with comparable economic systems did not get the benefits. 2/5

A new study finds that work-from-home raises fertility more than any conventional family policy.

"Estimated lifetime fertility is greater by 0.32 children per woman when both partners WFH one or more days per week as compared to the case where neither does." 🧵.
In this chart, a large effect is clearly seen, with fertility higher when either partner has some work-from-home and highest when both do.

The authors say this is not due to selection because fertility rose among those that unexpectedly got WFH, compared to those that didn't.

On this Christmas, we can reflect how Christianity was able to grow out of the ashes of collapsing Rome.

Scott Alexander reviews Rodney Stark's The Rise of Christianity and describes how the new faith won out by valuing women and children.
Important 🧵!
Much like our world today, Pagan Rome faced terrible birthrates.

Sex-selective infanticide was the norm. Women were not valued and many men just wanted to stay single.

It got so bad that Roman General Macedonicus proposed forcing people to marry! 2/7

Fertility and child populations are collapsing in left-leaning areas.

A new analysis by @FamStudies documents how marriage and childbearing are in steep decline among young liberals.

Given political trends, we may see big declines for national birthrates ahead. Important 🧵.
Media headlines across left-leaning media tell the story of growing anti-marriage and anti-child attitudes. 2/6

The Cradle of Europe, Fading Fast
Italy is at the center of our world, with more cultural and religious heritage than anywhere else on Earth.

How did Italy, once famous for its family culture, become the most aged country in Europe and what could turn things around? 🧵!
Italy's fertility in 2025 is just 1.12 births/woman, one of the lowest in Europe.

There are many statistics that help explain why the birthrate in Italy is so low, but one astonishing number stands out: Some 52% of Italian men aged 25-34 still live at home. 2/8

It has gone unnoticed that the most infamous school shooting in US history, the Sandy Hook shooting, may have had its origin in far left, antinatalist ideology.

Adam Lanza's recordings, found in 2021, expressed strong interest in antinatalism as well as p*dophilia. 🧵. Adam Lanza's YouTube channel "CulturalPhilistine" was not discovered until September of 2021, some 9 years after the shooting, after public interest had waned. At the time of the shootings, Lanza's motives were a mystery.

The YouTube channel contained only audio but matched recordings of Lanza's voice. The strongest evidence that the channel belonged to Lanza is that it includes long readings from a 35-page college application essay that Lanza had submitted on the topic of p*dophilia.

Lanza's first and fourth recordings were on the topic of antinatalism and "antinatal" appears 24 times in the transcripts.

"Life is suffering" appears in the title of another recording, and this is a key part of antinatal ideology. 2/6

One of the strongest predictors of fertility for countries is how many children most people consider to be ideal.

This shows that values around children drive birthrates strongly. We also see that actual fertility (1.48) is far below what people say they desire (2.36). 🧵

https://twitter.com/BirthGauge/status/1961174400516198542

Notice how strongly fertility ideals predict actual fertility, with the ideal number of children predicting 64% of a country's TFR.

Why does the US have a higher birthrate than Europe even though family policies are much more generous in the EU? A stronger desire for kids. 2/5

Published today, an important paper proposes a framework dividing total fertility rate into two component parts:
TFR = Total Maternity Rate (TMR) x Children per Mother (CPM)

This lens shows that virtually all recent declines in fertility were due to increasing childlessness. 🧵

Demographer @StephenJShaw realized that these two components of TFR, the total maternity rate (or equivalently, the childless rate) and children per mother move quite independently of each other.

That means one gets much more information from looking at both parts together. 2/6

All of China has low birthrates, but northeastern China has the lowest fertility of any region in the world, lower than South Korea. Why?
It was in these regions that the one-child policy was most rigorously enforced, completely wiping out natalism from the culture. 🧵 China's One Child Policy is gone now, and since July 2021, all birth limits have been removed.

But while the OCP was in force, millions of pregnant Chinese women experienced the tragic brutality of forced abortion, which I explored in this thread (2/5):

https://x.com/MoreBirths/status/1824662321358053877

Colombia has had one of the fastest fertility drops in the world, from 2.57 births/woman in 2000 all the way down to 1.2 in 2024.

How can it be that Colombia, with a GDP of 7K per year, has a fertility so much lower than the US? And why is this happening across Latin America? 🧵

https://twitter.com/JesusFerna7026/status/1945805119561363929

Colombia recorded only 445,000 births in 2024, way below UN projections of 701,000 births, for an official fertility rate of just 1.06 births per woman, and just 0.84 in Bogotá. (The true rate may be a little higher with unregistered births.)

Why such a dramatic collapse? 2/10

On this Father's Day, let's think of young guys and the future.

How can young men, most of whom really want children one day, boost their odds of achieving fatherhood?
🧵! Perhaps the first thing for young men to focus on is gaining income and building a career.
There is a strong positive relationship between a man's income and the number of children he will have.
This was true in the past and it is still true today, all over the world. 2/9

UPenn economist @JesusFerna7026 just gave an important talk called The Demographic Future of Humanity.
Key points:
(1) Birth data is much worse than the UN reports,
(2) UN projections are absurdly rosy,
(3) Economic growth will be low, and
(4) Immigration cannot fix this.
🧵 First, Fernández-Villaverde notes that in country after country, the UN's birth figures are far higher than what those countries officially report.

For example, the Colombian government reports births 25% lower than what the UN claims. In Egypt and Türkiye, the gap is ~12%. 2/8

Resisting Birthrate Decline Through Culture: How one part of Japan bucks the trend
Japan's woes are well known, its population long in decline, it's economy stagnating.
Yet one prefecture continues to grow, not through policy but through a pronatal culture.
🧵, please share!

For more than forty years, Okinawa has had far higher fertility than any other prefecture (Stone, 2024).

But Okinawa's fertility used to be lower than the 🇯🇵 average (map by @yz7sha).

How did Okinawa manage to develop a pronatal culture, so different from the rest of Japan? 2/9

A wonderful paper by Spears et al. showed that population reduction would have almost no impact on climate change.
Why? The main reason is that a baby born today will emit much less carbon than someone born a generation ago, and their children will emit even less carbon. 🧵

Most previous forecasts of how population would impact climate assumed that carbon emissions would continue at the same rate indefinitely.
But per-capita carbon consumption has been falling sharply and will fall even faster in the future as renewable energy takes over. 2/4

Knowing birthrates are driven by a stack of factors lets us figure out what is happening in each country and what its 👶 bottlenecks are.
Things like beliefs about children, marriage, housing conditions, religiosity, work culture and more all have a big impact.
🧵, please share! In Spain (TFR 1.12), big hurdles include a huge fraction of young people living with their parents (driven by relatively poor employment for young people), the high share of housing that is small apartments, and declining faith among the young. 2/13

https://x.com/MoreBirths/status/1809992234517033308

Fertile No More!
For more than a hundred years, Ireland was both the most religious and the most fertile country in Europe.
But in recent years, Ireland experienced rapid secularization, and its fertility fell to just 1.47 in 2024.
What happened to 🇮🇪, and what comes next?
🧵!

First, a bit of history.
By the 1800s, Ireland had become almost entirely reliant on just one crop. Potato blight struck in 1845, and soon famine and mass migration cut the Irish population from 8 million down to 4. Ireland's population is still well below its 1845 peak. 2/7

Getting old without ever getting rich
Thailand, with a TFR of just 0.95 in 2024, never even had a chance to get rich before its birthrate collapsed.
A look at how over-zealous family planning combined with cultural factors to put 🇹🇭 on a demographic downward spiral.
New 🧵!

Unlike its neighbors Korea and Taiwan, Thailand with a per-capita GDP of just $7000 never got to get rich before facing ultra-low birthrates.
For Thailand, the biggest cause was family planning run amok.
(Below, a wedding dress in Thailand made of entirely of condoms!) 2/9

The fastest fertility collapse in the world
In 2024 Chile recorded a fertility rate of just 0.88 births per woman, a drop of 23% in a year and 51% since 2015. No country has seen fertility fall as fast.
A look at how social changes have overwhelmed 🇨🇱 and threaten its future.
🧵!
In recent years, Chile has been wracked with protest. In 2018, there were some 151 feminist protests across the country.
Then from 2019 to 2021, these mixed with large youth-led anti-establishment protests, which turned violent and often resulted in brutal police responses. 2/7

South Dakota has the highest fertility of any US state and is the only state near replacement fertility.
Why is the birthrate so high in South Dakota and what lessons are there for the rest of America and the world?
🧵, please share!

https://twitter.com/LibertyCappy/status/1876859115441471931

First is religiosity. Some 50% of South Dakotans rate religion as very important in their lives, well above the US average of around 37%.
Higher religiosity is associated with higher fertility both in the US and worldwide. 2/10

How many people really understand the age-fertility curve?
A groundbreaking 2023 paper by Geruso et al. showed that fecundability (the ability of a woman to get pregnant) peaks at age 20 and has already dropped by 2/3 by age 33. This is far younger than almost anyone knew. 1/4

The most important way to solve the fertility crisis is to educate young people on how crucial it is to get started early on family. Achieving financial and career success may take a long time, but family can't wait very long! 2/4

https://x.com/MoreBirths/status/1829717318995210406

The Baby-Money Index (BMI) beats GDP
There is a new metric that is much better than GDP for comparing nations! The "Baby-Money Index" combines national income (GNI) and fertility rate (TFR) to produce a better measure of a nation's true health. (via Atoms vs Bits)
🧵! We've known for a long time that GDP and GNI don't fully capture how the people of a country are doing.

In an effort to better measure human thriving the Human Development Index (HDI) was developed by the UN in 2010. 2/6