PLUMMETING FERTILITY. “When people got richer, families got smaller; and as families got smaller, people got richer. Now, something similar is happening in developing countries. Fertility is falling and families are shrinking in places— such as Brazil, Indonesia, and even parts of India—that people think of as teeming with children. As our briefing shows, the fertility rate of half the world is now 2.1 or less—the magic number that is consistent with a stable population and is usually called ‘the replacement rate of fertility’. Sometime between 2020 and 2050 the world’s fertility rate will fall below the global replacement rate.”