[dumdumchan]

> fertility rates tend to fall below the level needed to maintain the population, 2.1 children per woman.

Why 2.1 and not 2?

[xadoc]

"The United Nations Population Division defines sub-replacement fertility as any rate below approximately 2.1 children born per woman of childbearing age, but the threshold can be as high as 3.4 in some developing countries because of higher mortality rates. Taken globally, the total fertility rate at replacement was 2.33 children per woman in 2003"

https://en.wikipedia.org/wiki/Sub-replacement_fertility

[jacob171714]

You've got a like 1/9 chance of dying by 21 I've heard. It's probably wrong but a decent amount of people die before they are able to have kids so they add a 0.1 to the replacement level.

[glimshe]

More like 1-2% in the US, you can check it using an actuarial table: https://www.ssa.gov/oact/STATS/table4c6.html

[taneliv]

I think at least infant mortality and gender imbalance at birth (more boys are born than girls) require it to be above 2.

[yakubin]

Some percentage of children are going to die before getting a chance to have their own children.

[cedilla]

0.1 kids per woman are expected to die without procreating.

[bambataa]

To account for people who die before reproducing.