ROSS DOUTHAT: The Case for One More Child: Why Large Families Will Save Humanity.

Start with the car seats. They hulk in the back seats of any normal sedan, squeezing the middle seat from both directions, built like a captain’s chair on Star Trek if James T. Kirk was really worried about taking neck damage from a Romulan barrage. The scenes of large-family life from early in the automobile era, with three or four kids jammed happily into the back seat of a jalopy, are now both unimaginable and illegal. Just about every edition of Cheaper by the Dozen, published in 1948, uses an image of the Gilbreth kids packed into the family automobile, overflowing like flowers from a vase. Today, the car seats required to hold them would take up more space than the car itself.

In his 2013 book, What to Expect When No One’s Expecting, Jonathan V. Last described “car seat economics” – the expense and burden of car seats for ever-older kids, the penalties imposed on parents who flout the requirements – as an example of the countless “tiny evolutions” that make large families rarer. Obviously car seats aren’t as big a deal as the cost of college or childcare, or the cultural expectations around high-intensive parenting. But it’s still a miniature case study, Last suggested, in how our society’s rules and regulations conspire against an extra kid.

Seven years later, two economists set out to prove him right. In a paper entitled “Car Seats as Contraception,” they argued that car-seat requirements delay and deter the arrival of third children, especially, because normal backseats won’t hold three car seats, so you basically can’t have a third young kid in America unless you upgrade to a minivan. The requirements save lives – fifty-seven child fatalities were prevented in 2017, the authors estimate. But they prevent far more children from coming into existence in the first place: there were eight thousand fewer births because of car-seat requirements in 2017, according to their calculations, and 145,000 fewer births since 1980.

Flashback: The Parent Trap. “Parenting was always hard work, of course. But aside from the economic payoffs, parents used to get a lot of social benefits, too. But in recent decades, a collection of parenting ‘experts’ and safety-fascist types have extinguished some of the benefits while raising the costs, to the point where what’s amazing isn’t that people are having fewer kids, but that people are having kids at all. . . . There’s also the decline in parental prestige over generations. My mother reports that when she was a newlywed (she was married in 1959) you weren’t seen as fully a member of the adult world until you had kids. Nowadays to have kids means something closer to an expulsion from the adult world. People in the suburbs buy SUVs instead of minivans not because they need the four-wheel-drive capabilities, but because the SUVs lack the minivan’s close association with low-prestige activities like parenting, and instead provide the aura of high-prestige activities like whitewater kayaking. Why should kayaking be more prestigious than parenting? Because parenting isn’t prestigious in our society.”