The Obvious-Once-You-Think-About-It Reason Why Education Cuts Fertility

As education goes up, fertility goes down. This rule works within countries: High-education individuals have fewer kids than low-education individuals. This rule works across countries: High-education nations have fewer kids than low-education nations.

Controlling for possible confounding variables does little to undermine the statistical strength of this negative relationship. In U.S. data, controlling for income makes the negative relationship between education and fertility stronger. Quasi-experimental estimates usually reinforce the common sense conclusion: Getting more education causes your fertility to fall.

What, though, is the mechanism? Economists routinely state with great confidence that education reduces fertility because it raises the opportunity cost of having kids. The more education you have, the higher your income; the higher your income, the more income to lose when you work less to care for another child. But even in terms of pure economic theory, this is a weak argument. Sure, education raises the cost of having kids; but education also gives you the income to more easily afford that cost. Yes, there’s an income effect as well as a substitution effect! Any economist convinced that education has to reduce fertility should also believe that education has to reduce the number of massages you get. After all, massages take time away from work, too.

Sociologists have a considerably better story: Education changes students’ values. Never mind rare heavy-handed propaganda about overpopulation. Education dethrones fertility via emphasis. Telling kids that academic and career success should be their top priority implicitly says, “And having kids should be a lower priority.” Not teaching religion and traditional values implicitly says, “Religion and traditional values aren’t very important.” And so on.

Though I’ve long preferred the latter story to the former, only recently did I realize that I’ve been overlooking a far simpler and practically bulletproof mechanism that explains why education reduces fertility. Namely: Almost everyone wants to finish their education before having kids — and there is a strong stigma against those who do otherwise.

If school ends in 12th grade, this norm lets you start having kids at 19 or 20.

If school ends after you get your B.A., this norm lets you start having kids at 23 or 24. (And since most students don’t finish on time, that should usually get bumped up to 26 or 27).

If school ends after your get your second Ph.D., this norm lets you start having kids around the age of 38.

Key point: Staying in school longer does nothing to alter the effect of biological age on fertility. The later you start having kids, therefore, the fewer kids you are ever likely to have. Late fertility almost automatically means low fertility.

Note: This mechanism also explains the standard result that women’s education cuts fertility much more than men’s education. Biologically, a man can work on his Ph.D. well into his 30s, finish, marry a woman years younger, and end up with a large family even though he followed the “Finish your education before having kids” rule to the letter. Not so for female Ph.D.s.

Is my mechanism really so novel? It shouldn’t be, but I’ve been pondering these issues for about twenty years, and I can’t recall anyone explicitly naming it as a possible explanation for the education-fertility connection.

All three proposed mechanisms behind the education-fertility link imply that societies can make babies with budget cuts. If governments cut education spending, education will fall, and fertility will rise. But my obvious-once-you-think-about mechanism implies an extra point of leverage: undermine the norm against students having babies.

But doesn’t that makes graduation harder? Without a doubt. Life is full of trade-offs. The trade-off rich countries ultimately face is between runaway credential inflation… and oblivion.

Haven’t seen Excalibur (1981)? It’s awesome. Here’s Morgana and Merlin.