Much energy has been devoted at the global and national level to explaining that the world is over-populated and that resource scarcity will cause dire problems in the future. Even my infrequent posts here about water could be interpreted to indicate that children should be few in any responsible family.
Ironically, there is reason to believe that it is precisely responsible families who should have many children. In this case, let’s allow the definition of many to be four. Why would 4+ kids make sense for a socially responsible family?
Population Replacement
It is well-understood that a population with an equal share of women and men will not achieve replacement unless its women average a fertility rate of 2.1. This presumes that 2 of the children each woman produces will go on to have 2.1 children of their own, with the residual 0.1 (or ~5%) being the portion of the population that will either die or otherwise not contribute to the population that will go on to reproduce in the next generation.
If all women in a population were equivalent, this would indicate that the optimal population replacement fertility would be 2 children per woman, with the occasional woman being allowed (perhaps by proven excellence or petition due to disability of one of her two children) to produce a third. This type of reasoning is being realized in China, which has long embraced a policy of allowing only one child per woman who wishes to gain/retain social benefits (approval, permissions, etc.). I understand from a personal conversation with a Chinese woman with an autistic child that in such cases, the state will approve the family producing an additional child, as replacement for the child who will not be able to leave a reproductive legacy. This idea of all families being limited to two children is seen also in fiction, as in Orson Scott Card’s Ender’s Game, where “third” has become a swear word.
Yet not all women are equal. The individual fertility of women in a population varies widely.
As a point of interest, the female fertility rate in the US is currently 1.9, below replacement, where it has stood for several decades.[ref]See Fertility rate, total (births per woman), The World Bank, available online at http://data.worldbank.org/indicator/SP.DYN.TFRT.IN, retrieved 28 Mar 2015.[/ref]
The Childless
One out of five white women will never have children.[ref]Gretchen Livingston and D’Vera Cohn, Childlessness Up Among All Women; Down Among Women with Advanced Degrees, Pew Research Center, 10 Jun 2010, available online at http://www.pewsocialtrends.org/2010/06/25/childlessness-up-among-all-women-down-among-women-with-advanced-degrees/, retrieved 28 Mar 2015.[/ref] However all races are approaching that 20% rate of childlessness by age 40-44 (when women may be expected to have ended their reproductive careers). For convenience, then, let us say that 5 out of every 25 representative women won’t reproduce at all. In order to achieve replacement, our 25 hypothetical women needed to produce 2.1 children apiece, or a total of 52 children. The remaining 20 still have to produce those 52 children.
One and Done
Another relatively large percent of women will only have one child.[ref]Brandy Zadrozny, America’s One-Child Policy, The Daily Beast, 17 Jul 2013, available online at http://www.thedailybeast.com/articles/2013/07/17/america-s-one-child-policy.html, retrieved 28 Mar 2015.[/ref] So from our hypothetical pool of twenty women, another 5 will have only 1 child apiece. For those keeping a tally, this means that 10 of our 25 hypothetical women have only added 5 children to the 52 children the group needs to produce to achieve population replacement. We are now down to only 15 women, who will between them need to produce 47 children.
Mothers without a Male Partner
Our 15 remaining women are not all created equal. One in four children under the age of 18 is raised without a father in the home.[ref]Single Mother Statistics, Single Mother Guide, 25 Feb 2015, available online at https://singlemotherguide.com/single-mother-statistics/, retrieved 28 Mar 2015.[/ref] This means ~13 of our original pool of 52 children is raised by a woman who doesn’t have a male partner. Almost half of these children raised by a single mother is living in poverty, compared to only one in eight raised by both a mother and a father.[ref]21% of children raised by single fathers is living in poverty, making them much more “similar” to mother-father families than to families where the mother has no male counterpart.[/ref]
Though single motherhood is more prevalent at 25%, it is hardly the new norm. The statistics are terrible for children raised by single mothers (poverty alone, even ignoring future prospects relating to avoiding jail and achieving societal success). If I use the numbers in the reference on Single Mothers, there are approximately 9.9 million mothers raising 17.4 million children without a father in the home (1.75). For every hundred single mothers, this would be like 75 mothers having 2 children and 25 mothers having only one child. This isn’t exactly equivalent to fertility rate, since there may be children in the households who are older than 18. We also don’t know how many single mothers were already included in the “one and done” category. But if I consider that 20 of my original women are mothers, and 1/4 of the children raised are in single-mother homes, then I have 13 (52/4) children with no father in the home in 7 families (13/1.75) with 2 of those children (7/4) being only children and the remaining five families without a father in the home producing 11 children between them.
Lots of math. Let’s just say that of our original 52 children we needed our representative pool of 25 women to produce, the 15 women in the first three groups (the childless, mothers (married or unmarried) with only one child, and single mothers of more than one child) have only produced 16 children.
This leaves it to the remaining 10 women to produce the remaining 36 children.
The Fertile, The Few, The Responsible
Our minority population of women who are mothers and functionally married[ref]Being actually married bodes well for still being in a relationship that functions as a marriage while children are being raised. However the data from which I am extrapolating do not specify that women who are mothers with a man in the home are necessarily legally married to the man who is in the home.[/ref] are now faced with the challenge of producing 3.6 children apiece. But it isn’t particularly useful to talk about fractional children, no matter what cruel jokes we might sometimes allow to cross our minds when faced by the actions of our relatives or progeny.
There will be those women who bear more than one child who will only have two children (since we’ve already accounted for childless women and those who only have one child). There will be those who have only three children.
It seems reasonable to consider that the number of women having fewer children would be higher than the number having more children, in part because everyone has been focusing on the 2.1 number as the ideal. Thus I can imagine my ten remaining women having a decreasing likelihood of more than 2 children, as shown below.
This would leave the mothers having more than two children feeling unusual and out of the ordinary, even if women with functional husbands are only socializing with other women who have functional husbands. But if we look at the experience of the children, we can see that the majority of them would have been raised in a family with more than two children, even if two-child households are the mode (in this simplistic assumption, 21 children are in families with only 1-2 kids, where 25 children are in families with 3 or more kids).
If I add up the number of children produced by this monotonic reduction in number of children, however, I don’t achieve my desired 36 children from those final ten women. I only get to 30 children (for a total of 46), which gives me a total fertility rate of 1.84 for my hypothetical group of 25 women – a number very close to the US fertility rate for the past couple of decades.
In order to achieve a fertility rate of 2.1 (given the current stats regarding women who don’t reproduce, women who are done with one, and women who don’t have a functional husband), I need more of my ten remaining women to shoot higher than 2, as shown.
So women who are in a marriage-like relationship with the father of their children should be aspiring to have 3-4 children, with those who can afford to support a larger family shooting for 5-6 children. This will also result in even more children experiencing family sizes of 3 or more children, with my replacement assumption, with 17 children in families with only 1-2 kids, and 35 children in families with 3 or more kids. Here the mode becomes 2-4, with the mode for children in mother-father households being 4 children.
Obviously my use of 25 individual women and not allowing for fractional babies results in some non-realistic artifacts. But the fundamental analysis holds.
Conclusion
Given the continued millions of people in the United States who don’t realize that an average fertility rate of 2.1 means women should have more than 2 children, intelligent married couples should be planning to bear 4 children.[ref]The Pew Research Center article contains data showing that educated women are now less likely to remain childless, apparently indicating that smart women have begun to figure out that they are not the ones who should be “taking one for the team” by remaining childless. See Gretchen Livingston and D’Vera Cohn, Childlessness Up Among All Women; Down Among Women with Advanced Degrees, Pew Research Center, 10 Jun 2010, available online at http://www.pewsocialtrends.org/2010/06/25/childlessness-up-among-all-women-down-among-women-with-advanced-degrees/, retrieved 28 Mar 2015.[/ref]
Women (girls) without a functional husband who cannot afford to provide for children should continue to strive to remain childless, leaving impoverished single mother status to those unfortunate women who lose a functional husband through death or divorce/abandonment.
Given that at a fertility rate of 1.9, the United States is missing over 6 million children to achieve replacement, extraordinary women (and their husbands) should feel no guilt having as many children as they can appropriately manage.
PS – An inability to achieve population replacement creates multiple social problems such as inability of the working generation to support the benefits owed to the retired generation and a vacuum with regards to workforce that encourages immigration of all forms, including illegal immigration. However it is presumed that people reading this post are already familiar with these facts.