One interesting thing about birthrates that I think most people haven't really looked at is the data segregated by age groups.

In most countries with falling birthrates (save some exceptions like Japan) a huge part of this decrease is in the 15-25 age group. There is usually also a decline in the 25-29 but there's an increase or the same rates as we've had historically on the 30+ range.

What this mean is basically that we've eradicated teen pregnancy, and that's definitely something desirable in a developed society.

A sustainable population - not increasing just staying the same - requires each and every single female have more than 2 children on average.

Starting in your 30s, especially later 30s makes this extremely difficult. It takes months of perfectly hitting ovulation windows to get pregnant, and then you generally want at least ~9 months between children, so you're looking at ~2 years per child, all while fertility starts to rapidly decline as you head into your 40s.

The long and short is that a sustainable population is going to require the majority to start having children in their 20s. That figure going down has nothing to do with teen pregnancy.

> It takes months of perfectly hitting ovulation windows to get pregnant

30% of couples who don’t use birth control and who have regular sex get pregnant within one month.

60% get pregnant within three months.

80% get pregnant within six months.

What is the age of those couples?

~33% of pregnancies result in miscarriage. Most women who have tried to have kids have had one, sometimes even more.

As a peer alluded to, that's going to be for some ideal demographic in their twenties (probably early), hitting ovulation perfectly. Age changes things dramatically:

"Women younger than 30 have about a 20 percent chance of getting pregnant naturally each month. By age 40, the chance of pregnancy is about five percent each month." [1]

Things like IVF do not dramatically change the odds either. They're better of course, but it's far from guaranteed - it's still just a rather expensive roll of the dice.

Then on top of all of this, having children later greatly increases the chances of miscarriage, developmental issues (like Down syndrome) and so on.

Life's brutal here - you're in a race against time, yet the later you start the longer it takes, and the harder it becomes.

[1] - https://www.yourfertility.org.au/everyone/age

N=1 anecdata here, but... My wife and I got pregnant -- both times -- during the first month of trying. We were mid-30s, myself being 3 years older than she is, and my wife was old enough at the time of conception to have had a "geriatric uterus" and our first pregnancy, spontaneous fraternal twins, was considered "high-risk" out of the gate because of her age.

> Things like IVF do not dramatically change the odds either. They're better of course, but it's far from guaranteed - it's still just a rather expensive roll of the dice.

Sadly, literally all of our peers who were trying and having kids in the same demographic as us, +/- a few years, struggled hard and most needed fertility treatments. At least 2-3 of them were never able to conceive, despite the expensive and time-consuming treatments. It's brutal.

I will also add, I have a number of friends who are >= 10 years younger than I am and many of them also struggled with miscarriages in their late 20s while trying to start families.

I am all for preventing teen pregnancy, but the data sounds more like young people can't afford having children so they are waiting longer.

They couldn't "back then" either, I would argue.

"back then" a family could live on a single income.

Common misconception. Poverty levels were far higher. In 1950 half the global population lived in abject poverty. Today, it's less than 10%.

https://ourworldindata.org/poverty

Some people could. There was also a lot more abject poverty.

They had to. Outside a few vocations, women weren’t allowed to work.

And now they have to work because a single income is no longer enough. Yay for progress.

This was largely for relatively privileged people. Most families the mother worked as a teacher, nurse, domestic, secretary, nanny, etc.

Working a minimum wage could buy a starter home "back then". It now can hardly pay rent, and starter homes essentially no longer exist, even if someone wanted one.

It's not just that young people can't afford to have babies is that women in the 20-29 range are either studying or entering the work force.

These are extremely important years for career building.

It's more about the fact that young women are choose to build their education and career (like men do) rather than have children.

Most children were born from parents in their 20s though… I don’t know you spin this when one age group stays the same and all others drop.

No, if there is also a decline between the ages of 20-29 then the implication is not that we've eradicated teen pregnancy. It's that people are not having as many kids. When you have kids in your 20s you can have more than if you start in your 30s

>implication is not that we've eradicated teen pregnancy.

>a huge part of this decrease is in the 15-25

It is.

15-18 is only a fraction of 15-25...

the thing is, this is happening across any remotely wealthy or developed country, and in that sense the US is actually the ninth highest birthrate in the OECD and well above the average. The only OECD country with fertility rates above 2 is Israel, and that's mostly because the ultra-Orthodox have really high birth rates.

But the birth rate is on par with the rivals it’s being compared to in this article/thread.

Children just aren’t that expensive.

Most of the significant expenses people describe are optional. It is more rational to match your spending to what you can afford with howevermany kids than it is to match the number of kids you have to an arbitrary lifestyle.

I think this varies wildly depending on where you live. Where I live (Melbourne), just the cost of suitable housing (a/ near a school, b/ close to most jobs, and c/ with space for 1+ children) is so high that it makes it difficult for a lot of couples to even consider children.

https://www.abc.net.au/news/2024-06-04/why-australians-arent...

But it wasn't cheap "back then" either. I've spent 1 hour one way riding 2 buses to school (same as my parents to work). We had 62 m^2 (670 sq. ft.) of house for 2 parents + 3 children.

It's just now we suddenly consider that too bad. Back then it was normal, just like everyone else.

I don’t know where you were born and how old you are, but that situation was defiantly not usual when i was a child (born 1983 in Israel). If anything I think I’d need a startup-liquidity-event level windfall to be able to afford housing as spacious as my parents bought in the 80s (housing costs increased way more than wages).

It may have been when my parents were born though (mid 1940s, one in what is now Israel and the other in what was then the Soviet Union).

But your parents didn't live in Israel 2019. Israel 1983 was more like today's Venezuela or Argentina. If you move today to a place comparable to Israel in 1983, you'll be able to afford even more space than your parents.

Not sure why 2019 specifically, it's 2024. I think you also underestimate 1980s Israel - although there was a stock-market crash in 1983, it was not otherwise that poor- maybe more like today's Portugal or Greece than Venezuela.

But anyway my parents were 1983 Israelis, they didn't come with future-Israel purchasing power - so they were able to afford their housing on the income of the time :) Other kids in my class had ± similar housing. Some were poor and had worse housing, but not 5 people in a 62m flat level of poverty- for that to be common you had to go back another couple decades (e.g. my mother's childhood experience in the 40s-50s was more like that, might have been common up to the 60s).

> Not sure why 2019 specifically, it's 2024.

Because in 2019 real estate was not only expensive by itself, but also all the future growth was added to a price.

Today in 2024 you can buy very cheap in some places (north, for example).

> there was a stock-market crash in 1983

Not just stock-market. By the time of the crash, Likud laid waste to the whole economy to undermine "the left".

what is space for a child? In previous decades it was acceptable for kids to share rooms via bunk beds.

Kids can share a room but that still means an extra room, which has a cost. Plus kids come with stuff like clothing, toys, school supplies, etc.

Eurostat [0] would have you believe that you need 3 rooms for a family of 2 adults and 1 child. That's fine as an aspirational goal, but I feel that parents with a toddler living in a signle-room flat is good enough, especially for the baby.

[0]: https://ec.europa.eu/eurostat/statistics-explained/index.php...

I never had my own room. Up until age of 14 I slept on bunk bed sharing a room with my brother and my parents, so it doesn't always mean a separate room.

If you don't own a home you have to rent and they simply won't and can't legally rent you too small an apartment or one with insufficient bedrooms.

In practice having 2 or 3 kids is going to mean going from studio/1 br to 2/3 br and double or triple housing costs.

That seems draconian. Is that a US federal/US state/other country law?

Same in Germany. There are minimum requirements on the living area for children.

State by state but the same most places. Even if the law would let you are you going to raise a family in your 350 sq studio?

They aren't in 'traditional' households where at least one parent stays at home. Without that daycare/nanny and other costs can become very significant. It's also not just daytime stuff. Babies need to feed every 2-3 hours, including at night, and each feeding session can be quite lengthy. That doesn't synergize so well with getting a full night's rest to go join the rat race the next day.

>That doesn't synergize so well with getting a full night's rest to go join the rat race the next day.

I feel this in my bones as I read this while rocking my infant who won't sleep for the last 2 hours.

This. Every time I hear parents in SF Bay Area complain that kids are too expensive, I ask them what are they spending -- turns out they consider stuff like private school a necessity. The bar of "normal" is raised significantly, that's it.

Who takes care of the kids while the parents work?

Americans are largely solving this problem by not having children, or only trying to have children when it’s financially easy but medically difficult.

Automation may actually be the answer to a declining birth rate, and we might stabilize at a much lower world wide population as a result (say 4 rather than 8 billion). People will complain less about Waymo stealing jobs when there are no uber drivers left, but we really aren’t there yet, we still have a surplus of labor.

(not a reply to seanmcdirmid) I couldn't reply directly to 'ayewo's post, so I reply here: I'm not sure where you are finding birthrates are climbing elsewhere. The forecast for most of the planet is birth decline over the next 50 and 100 years. Africa will mainly still contribute to population growth, but a lot of other areas/countries are headed for net decline in population, with the results hitting us in 50 and 100 years. It is not necessarily all bad, if we cope with it in relevant ways - a "solution" that was based on populations steadily forever climbing wouldn't be sustainable anyway, for many reasons.

Your opening sentence was well articulated.

But I’m not so sure about your second sentence. How does a situation where world wide population drops to 4 billion come about?

Even if US birth rates are declining, birth rates are climbing elsewhere so I’m struggling to see how in aggregate, the world population declines to half of what it is today.

> birth rates are climbing elsewhere

Where are birth rates climbing? Narnia?

Africa

Not enough to compensate for everywhere else plus even there most countries are tapering off.

[citation needed]

Every source I've looked at shows a drop in fertility.

Birth rate is a somewhat ambiguous term. Does it mean number of births? Or does it mean number of births per person?

You're talking about fertility rate, which is number of births per person. That's decreasing everywhere.

ayewo may have been talking about number of births. That is increasing in Africa, but even with Africa, is still decreasing in total worldwide:

https://ourworldindata.org/grapher/annual-number-of-births-b...

I'm pretty sure birth rate is universally seen as a second order thing rather than a first order thing.

What are you referring to by "birth rate"? Are you referring to the general society-wide system of babies being born? Or are you referring to a specific metric relating to how many babies are born?

From definitions I find online, first order vs second order refers to systems. So if you're applying those adjectives to a specific metric, I'm not sure that's correct.

I don't think we can say that people "universally" agree about what metric the term "birth rate" should refer to, because different people in this thread are using the term to refer to different metrics. However, I do think that generally the term "birth rate" refers to the number of babies born per year (or other unit of time), and the term "fertility rate" refers to the number of babies born per woman. Fertility rate is actually somewhat more complicated than that, because it takes into account the different fertility rates for women of different ages, and then sums those together, to simulate how many children a woman would have who passes through all the different ages.

https://en.wikipedia.org/wiki/Birth_rate

https://en.wikipedia.org/wiki/Total_fertility_rate

Not climbing coming down, but still high

not op but i think the climate catastrophe will curb population extensively. on the one hand by simply killing a lot of people directly (mostly war, famine and displacement), on the other hand by reducing birth rates (i.e. people not wanting to have children when there's not hope for the future).

Unemployment is low, labor force participation is high. We do not currently have an excess of labor, and a good deal of the reason that we had inflation was that there was no pool of waiting labor to soak up money injected into the economy during covid -- so instead that money bid up prices.

We have uber drivers complaining about too many people driving for uber in my area, so I don't think waymo would be welcome. We still have people who are unemployed or underemployed, for whatever reason, and automation pushes have huge resistance (e.g. dock workers in America don't want automation to hit ports like they have in China).

You are never not going to have some people who are unemployed. Don't mistake that for the idea that the economy is demand-constrained. It's clearly not right now, and automation of Uber workers would certainly make someone unhappy, but it would also very clearly lead to economic growth and vastly more people being better off than worse off.