— A return to "normal" growth is unlikely: Economic growth of 3 percent a year in developed countries, the average over four decades, had been considered a natural rate of expansion, sure to return once damage from the global downturn faded. But many economists argue that that pace can't be sustained without a surge of new workers. The Congressional Budget Office has estimated that the U.S. economy will grow 3 percent or so in each of the next three years, then slow to an average 2.3 percent for next eight years. The main reason: Not enough new workers.
— Reduced pay and lifestyles: Slower economic growth will limit wage gains and make it difficult for middle-class families to raise their living standards, and for those in poverty to escape it. One measure of living standards is already signaling trouble: Gross domestic product per capita — the value of goods and services a country produces per person — fell 1 percent in the five biggest developed countries from the start of 2008 through 2012, according to the World Bank.
— A drag on household wealth: Slower economic growth means companies will generate lower profits, thereby weighing down stock prices. And the share of people in the population at the age when they tend to invest in stocks and homes is set to fall, too. All else equal, that implies stagnant or lower values. Homes are the biggest source of wealth for most middle-class families.
Births might pick up again, of course. In France, where the government provides big subsidies and tax breaks for children, birth rates are back where they were in the early 1970s. In other countries, women who put off having children in the recession might play catch up soon, as they did after World War II. Demographers note that women were having children later in life even before the crisis, and so births are likely to rise anyway.
But even a snapback in births to pre-recession levels will leave families much smaller than they were decades ago, a shift that has already affected industries and economies around the world.
In Japan, sales of adult diapers will exceed sales of baby diapers this year, according to Euromonitor International, a marketing research firm. In Germany and Italy, towns are emptying as families shrink and there aren't enough children to replace older ones who are dying. And in South Korea, where births have fallen 11 percent in a decade, 121 primary schools had no new students last year, according to Yonhap, the country's government-backed news agency.
Park Hyun-kyung, a 34-year-old hospital administrator in Daegu, South Korea, says she would like to have three children, just like her parents. But she and her husband have decided to stick to one, if they have any.
"Most jobs are not secure enough to allow couples to have a baby and raise kids," she says.
In China, where the working-age population is set to shrink next year, the government is relaxing a policy that had limited many families to one child. It might not help much. Chinese are choosing to stick to one on their own.
Lei Qiang, a logistics manager in Shanghai with a 2-year-old daughter, has ruled out another child. "I just couldn't think how expensive it is to have two," says Lei, 39.
Economists are worried not just because growth is stalling in working-age populations. Their numbers as a share of the total population in many countries is falling. Economists like to see this share of total population rise, because it means more people are earning money, expanding the tax base and paying for schools for the young and pensions and health care for the old.
Before the recession, the number of these potential workers as a proportion of total population was falling in three of the world's six biggest developed economies — Japan, Germany and Italy. Now the proportion is also dropping in the United States, France and the United Kingdom, according to investment firm Research Affiliates, using data from the United Nations.
Economists say it is rare for the number of working-age people as a share of the total population to fall in so many major countries at the same time. It's usually because of war and famine, although such proportions also fell in the 1950s as baby boomers were born and populations surged. The six countries with declining proportions of working-age people now, plus China, accounted for 60 percent of global economic output in 2012, according to Haver Analytics, a research firm.
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