Introduction

Attempts to understand the decisions people make about whether and when to bear children have been vital to the work of demographers and other population scientists for many decades. Yet, despite a vast amount of attention to the issue, progress towards a clear appreciation of what motivates people to have children, and the processes by which they arrive at decisions about fertility, has been, at best, fitful. In the classical version of demography's grandest theory, that of the demographic transition (Notestein, 1945, 1953), the immediate causes of the decline in fertility were less clearly specified than were the causes of the decline in mortality. Even after more than half a century's debate, there is still no consensus about why fertility falls during industrialisation, with some favouring accounts based on a reduced demand for children (Easterlin & Crimmins, 1985) and others advocating a narrative based on the diffusion of new ideas about the acceptability of birth control (Cleland & Wilson, 1987).

Demographers' imperfect understanding of the ways in which decisions about childbearing are made and the factors which determine them reveals itself in discussions about policies and programmes designed to influence fertility. In relation to those countries where fertility is still well above replacement level and population growth is rapid, a great deal of the debate has, at least until recently, taken place at a fairly crude level, focusing simply on the relative importance of family planning programmes (on the one hand) and social and economic changes (on the other) in initiating and maintaining fertility decline.