As of 2006, there are an estimated 6.5 billion people on the planet and by 2012 this number will reach 7 billion. For decades, alarmists have warned of an overpopulated world with insufficient resources and , indeed, this threat remains. It is ironic, then, that for more and more developed countries the main demographic challenge is not overpopulation, but a declining one. Though the reasons for falling birth rates vary from country to country,all countries with declining populations face similar social and economic consequences