Fertility in high-income countries has been declining for a hundred years, with few exceptions, and in many areas, it is now extraordinarily low. In Germany, Italy, Japan, and Spain fertility has been well below 1.5 for more than two decades—lower than the average of just over two children per woman needed to maintain a stable population size. This means that each new generation is less than three-quarters the size of the preceding one. Such ultralow fertility makes for a rapidly rising older population and poses challenges for governments, economies, and the sustainability of social security systems. Substantial ... (full story)