Birth Dearth.

EUROPE; ITALY; SPAIN; GERMANY; UNITED States

The article discusses how the United Nations recently warned that many of the world's cities are becoming hopelessly overcrowded. At a conference in London, the U.N. Population Fund found that unless something dramatically changes, the world's 50 poorest countries will triple in size by 2050, to 1.7 billion people. Across the globe, people are having fewer and fewer children. Fertility rates have dropped by half since 1972, from six children per woman to 2.9. And demographers say they're still falling, faster than ever. The world's population will continue to grow, from today's 6.4 billion to around 9 billion in 2050. But after that, it will go sharply into decline. Most of us are familiar with demographic trends in Europe, where birthrates have been declining for years. To reproduce itself, a society's women must each bear 2.1 children. Europe's fertility rates fall far short of that, according to the 2002 U.N. population report. Italy and Spain, at 1.2, bring up the rear. In between are countries such as Germany, whose fertility rate of 1.4 is exactly Europe's average. With an expected median age of 44 in 2015, China will be older on average than the United States. By 2019 or soon after, its population will peak at 1.5 billion, then enter a steep decline. By midcentury, China could well lose 20 to 30 percent of its population every generation. As the United Nations reported last week, people everywhere are leaving the countryside and moving to cities, which will be home to more than half the world's people by 2007. Once there, having a child becomes a cost rather than an asset. Increasing female literacy and enrollment in schools have tended to decrease fertility, as have divorce, abortion and the worldwide trend toward later marriage. Contraceptive use has risen dramatically over the past decade; according to U.N. data, 62 percent of married or "in union" women of reproductive age are now using some form of nonnatural birth control.