Fertility rates have fallen in countries with woeful economies, such as Greece and Italy. But they have also fallen in countries that sailed through the financial crisis, such as Australia and Norway. Although the American baby bust was expected, the lack of recovery after seven years seems odd. “I was fairly confident that women were just delaying births, and that we would see a rebound,” says Mr Johnson. “I'm beginning to wonder now.” In Britain the drop came late: the fertility rate fell from 1.92 to 1.81 between 2012 and 2014. Then there is France, where couples looked at the economic slump and shrugged. The fertility rate there has barely moved.
If some of the international trends are hard to fathom, so is the strange uniformity within countries. Trude Lappegard, a Norwegian demographer, says that her country's baby bust, which has been going on for six years, might be easy to explain if it had hit one group especially hard. Instead, women of all ages and all levels of education are having fewer children
One possible explanation is that immigrants are not boosting birth rates much these days, and might even be dragging them down. Some demographers suggest that cuts to welfare might have made poor mothers warier of having children. But that does not explain the behaviour of middle-class women. And family support has actually become more generous in some countries with falling fertility.
Ann Berrington of Southampton University points to housing. Young and even not-so-young couples find it hard to buy property in England and Wales: 46% of 25- to 34-year-olds lived in private rented accommodation in 2014-15, up from 24% a decade earlier. Four in ten 24-year-olds still live with their parents. Home-ownership rates have fallen in America and Australia, too. The rate is rising in France, where fertility has held steady—though that might be thanks to strong pro-natalist policies.
You can have a baby in a rented flat, of course. But in a country like Britain, where earlier generations found it easy to buy homes, that seems to flout a psychological rule for some. In the 1960s Richard Easterlin, an American economist, suggested that people would avoid having children if they felt unable to bring them up in a style that at least matched the way they were raised. It might be time to dust off that idea.
Some couples could be delaying having babies not because they cannot afford them, but because of a vague feeling that family life is harder than it used to be. A Pew poll of 11 rich countries last year found that 64% believe that today's children will be worse off than their parents. Perhaps the gloom has spread even to countries with strong economies. Mr Sobotka suggests that Scandinavians could have overreacted to repeated news reports about hard times elsewhere in Europe. “It gets below people's skins,” he says.
In this, childbirth might be a little like politics. When a surly, anti-politics mood first took hold in Europe and America after the financial crisis, it was tempting to think it would dissipate as economic growth returned. Today Donald Trump is the probable Republican presidential nominee in America, the National Front is rampant in France and the British government is fighting both Scottish separatism and Europhobia. Bad moods can linger.
Whether and when birth rates bounce back, and how high, has broad consequences. America's Census Bureau simply assumes that current fertility rates will persist. Since 2008 it has slashed its prediction for the country's population in 2050 from 439m to 398m. If lower fertility lasts, it would help balance government accounts in the short term, because there would be fewer children to educate, but hurt in the long term. A fertility rate of 1.8 would mean twice as large an annual social-security deficit by 2089 as one of 2.2, as a percentage of the social-security tax base.
A persistent slump would also be bad news for nappy-makers. But the overall effect on the market for baby gear might be surprisingly slight. Marcus Tagesson, the boss of Babyshop, a Stockholm-based retailer, says that the important thing is that couples have at least one child. The first baby is the most profitable, he explains. Parents want everything to be new and perfect; besides, they make mistakes with their first-born that they do not repeat. Such as? “White clothes,” says Mr Tagesson, a little ruefully.