It Will Take a 3-Child Norm Just To Reach Replacement Fertility

By @MoreBirths (

In a future world where 1/3 of women wind up childless (a fairly middle-of-the-road figure) the remainder will need to have three children each just for society to be at replacement

The brilliant demographic data scientist @BirthGauge ( has created a new chart that shows the distribution of births by birth order across various countries. It is great for understanding typical family sizes.

Since almost nobody has seen a chart like this before, @BirthGauge offers some helpful advice for how to interpret it.

And what this chart shows is that there is a strong family size ‘norm’ of two children in almost every developed country. If the family size norm is 2 kids and a large share of women are childless, then TFR will be well below replacement As @Empty_America and @ludditeautist astutely observe, if there is a two-child ideal, actual fertility will be well-below replacement. This is especially true since unintended pregnancies are way down due to the widespread availability of very effective birth control.

For example, in the United States, if the fertility rate among women who have children is about 2.15 (close to a two-child ideal) and one quarter of women end up childless, then the total fertility rate will be ~1.61. And that is almost exactly what we see!

Indeed, in virtually every developed country where modern birth control is widely available, fertility rates are far below replacement. For example, almost every European country bunches in a tight group at between about 1.3 and 1.7 births per woman.

What explains this remarkable result? Simply put, there is a 2-child ideal combined with quite a bit of childlessness.

But what about countries like Korea, Taiwan and China? A lot of people in those countries have a one-child ideal, which is directly due to one-child propaganda and policies. If you combine lower family size ideals with a lot of childlessness, these incredibly low fertility rates are the result.

We should do all we can to address unplanned childlessness

Data analyst and filmmaker @StephenJShaw in his Birthgap documentary shares the heartbreaking stories of many people who had hoped to have children but could not.

There are a number of ways to reduce unplanned childlessness. As Shaw explains in numerous interviews, education of young people is key, especially regarding the very high risk that people will run out of time to start a family if they are not intentional about and focused on partnering and starting a family before fecundity wanes.

High rates of childlessness are here to stay

Still, it is likely that very high rates of childlessness are here to stay. We can’t go back to the world of the 1950s. During the Baby Boom, very high rates of marriage at quite young ages ensured that almost everyone had children. My thread on what caused the Baby Boom explains this.

It is said that the past is a foreign country. Can anyone imagine women these days getting married at an average age of 20 as they did then?

Now there is a vast education gap as far more women obtain college degrees than men and highly educated women struggle to find suitable partners.

Meanwhile a significant portion of men and women have adopted explicitly anti-natal views as I detailed in two recent posts on fertility and culture. These people are not having children any time soon.

The only way the numbers work is if there is a higher norm among those who do have children

These days, “accidental” pregnancy is getting less and less common. In the past, people did what came naturally and children were the result.

Since there is little appetite to roll back the availability of birth control and return to the world of very high unplanned pregnancies (many of which were teen pregnancies) the only way forward is through much higher fertility intentions. In short, intentional pro-natalism in culture will be essential for advanced societies like ours to thrive.

In a future world where 1/3 of women wind up childless (a fairly middle-of-the-road figure) the remainder will need to have three children each just for society to be at replacement.

But that is not such a strange concept. As the below-linked post shows, there was always a significant rate of childlessness in the past — combined with families that had a lot of children. If we are to solve the low fertility crisis, bigger families will have to become the norm again.

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