MATTHEW YGLESIAS at Slate discusses a fascinating new paper in the Journal of Economic Literature that asks "Why is the teen birth rate in the United States so high and why does it matter?" The authors, economists Melissa Schettini Kearney of the University of Maryland and Phillip B. Levine of Wellesly, find that having children as a young, unmarried woman doesn't much hurt one's economic prospects. It's true that young, unmarried women who beget don't exactly thrive economically. But that's not motherhood's fault. Ms Kearney and Mr Levine ingeniously use data on miscarriage to more precisely isolate the economic effects specifically due to motherhood from those effects due to other demographic and socioeconomic attributes that may also affect the decision to have a child. They find that young, single women who miscarry don't do significantly better than similarly situated women who don't. Nor do teen moms fare significantly worse than their child-free sisters, whom they tend to closely resemble in most relevant respects. All of which is to say, the alternative to the poverty of teen motherhood tends to be child-free poverty, not child-free non-poverty. As Ms Kearney and Mr Levine put it:

[B]eing on a low economic trajectory in life leads many teenage girls to have children while they are young and unmarried and that poor outcomes seen later in life (relative to teens who do not have children) are simply the continuation of the original low economic trajectory. That is, teen childbearing is explained by the low economic trajectory but is not an additional cause of later difficulties in life. Surprisingly, teen birth itself does not appear to have much direct economic consequence.

So why is there so much teen motherhood in America? Mr Yglesias summarises the papers' findings:

[T]een girls whose mothers have little education are much more likely to give birth than girls with better-educated mothers. Even more interesting is the way that economic inequality amplifies nonmarital births to teen moms. In particular, “women with low socioeconomic status have more teen, nonmarital births when they live in higher-inequality locations, all else equal.” The measure of inequality used here is not the fabled gap between the 1 percent and the 99 percent, but the gap between the median income and incomes at the 10th percentile. It measures, in other words, the gap between poor people and the local typical household.* It may be a proxy for how plausible it would be for a girl from a low-income household to rise into the middle class. The more difficult that rise seems, the more births there are to unmarried teens.

Mr Yglesias then concludes that "family life seems to follow real economic opportunities. Where poor people can see that hard work and 'playing by the rules' will reward them, they're pretty likely to do just that. Where the system looks stacked against them, they're more likely to abandon mainstream norms."

I'm less sure about the causal story here. As far as I can see, the story is just that teen motherhood goes up when the perceived cost of teen motherhood goes down. What role is bottom-to-middle inequality really playing in the story? As Ms Kearney and Mr Levine note, rates of teen motherhood have declined dramatically in the past two decades. Yet bottom-to-middle inequality has barely changed at all. So something other than bottom-to-middle inequality is out there affecting things a lot. As they also note, other indicators show rising inequality. Did the runaway incomes of the top 1% decrease teen motherhood?! They don't think so, and neither do I.

Mr Yglesias mentions norms. Perhaps it's the case that the larger the proportion of folks at the tenth percentile who happen to think working hard and "playing by the rules" will benefit them, the smaller the income gap between bottom and middle and the larger the perceived cost of teen motherhood. Though they bring up possibilities in this general neighbourhood, I don't see that Ms Kearney and Mr Levine have done anything to rule this hypothesis out. Indeed, why not say that poorly-educated mothers, high bottom-to-middle inequality, and high rates of teen motherhood all have a common cause: a certain kind of culture. In that case, not having kids doesn't help poor teen girls economically because they're stuck having internalised a culture of economic stasis either way, kids or no kids. Isn't this what Charles Murray would say? Why shouldn't we join him in saying it?

The main reason not to say this sort of thing, I take it, is that it's quite plausible that culture is determined in no small measure by material factors. In that case, a cultural explanations isn't an alternative to an economic explanation. Perhaps it's this sort of materialist thought that leads Mr Yglesias to say that "Preaching good behavior won't do anything to reduce" teen motherhood. Preaching doesn't change the "real economic opportunities" that determine whether young women adopt or "abandon mainstream norms". Preaching is a cultural approach to a fundamentally economic condition.

Now, I'm persuaded that the causality also goes the other way; economic conditions both determine and are determined by culture. We're on a dizzying merry-go-round of reciprocal causation with no hope of getting off. Still, preaching may remain the wrong kind of cultural intervention, even if the "problem" has a large cultural component. Indeed, there may be no feasible cultural solutions to some cultural "problems", and teen motherhood could be one of them. Even if cultural solutions are available, none of them may be the sort of thing policymakers can do anything about. Beside the mysterious, unexplained factor responsible for the decline in teen motherhood over the past 20-some years, the only things Ms Kearney and Mr Levine found to have any real influence on rates of teen motherhood were "expanded family planning services through Medicaid and reduced welfare benefits". The combined effect is small, accounting for only "12 percent of the decline in teen childbearing between 1991 and 2008", but that's not nothing.

Perhaps we'll be less eager to combat teen motherhood now that we understand that it doesn't much harm the economic prospects of the young women most likely to go in for it. My own reaction to this news is to wonder whether it isn't cruel to try to discourage relatively poor teen girls from seeking the comforts of motherhood, if motherhood won't hurt their prospects. If we set aside as ill-founded our paternalistic economic motivations to reduce rates of teen motherhood, only the impulse to discourage the proliferation of those people and/or that culture seems to remain. I'm not comfortable with that. But if we wish to reduce teen motherhood anyway, we ought do more of what has been found to work. So poor young women should have access to birth control, including abortion, at no cost. And welfare transfers to teen moms should be reduced.

Of course, the former proposal would evoke hysterical opposition from the right, and the latter, hysterical opposition from the left. Neither seems remotely politically possible, which leaves us for all practical purposes precisely where we would be if we didn't care very much about teen motherhood. So perhaps we should take the hint, put the "problem" out of mind, and see if the mysterious forces that have been driving the decline in teen motherhood continue to do their mysterious work.

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