World demographic trends. Population Division of the Department of International Economic and Social Affairs, United Nations Secretariat.

The world population almost doubled over the period 1950-1985. The rate of population growth, however, changed its course from the rise in the 1950s and 1960s to the decline in the 1970s and the first half of the 1980s, with a turning point around 1970. This is mainly due to the fact that significant fertility reduction started in many countries in Latin America and Asia during the period centred around 1970. The age structures of those countries became younger in the 1950s and 1960s, due to the considerable reduction in infant and child mortality, and then increasingly older in the 1970s and 1980s, mainly due to the fertility decline. Again, the turning point was around 1970. The proportion of population living in urban areas is increasing in most countries of the world. The level of urbanization is lower but the pace of urbanization is faster in the developing regions than in the developed regions. Africa has a different demographic profile from Latin America and Asia. Significant fertility decline has not started in the majority of countries in Africa, and mortality, although still very high, is declining particularly for infants and children, resulting in very high growth rates and increasingly younger age structures. In contrast, populations of the developed regions are characterized by low rates of growth, low levels of fertility and mortality, and an increasing proportion of older persons. A number of countries have below-replacement fertility levels and are projected to reach zero or negative population growth in the near future. This will reduce the proportion of the world population living in the developed regions from one-third in 1950 to one-sixth in 2025.