Resumen

To what extent does reduced child mortality explain the fertility transition in developing countries? Is decreasing child mortality a prerequisite-a necessary condition-for decreasing fertility? May decreasing child mortality trigger by itself-as a sufficient cause-the fertility transition? Answering these questions is important to understand the dramatic demographic changes currently underway in developing countries and to guide population and health policies. If improving child survival is a precondition for birth control, family planning programs in the least developed regions are unlikely to succeed, especially if these programs have a vertical organisation independent of child health interventions. In turn, if reducing child mortality is a sufficient condition, family planning programs may be somewhat superfluous and there would be grounds for the statement that "development is the best contraceptive." A book published about twenty years ago (Preston, 1978) is a landmark for the study of the effect of child mortality on fertility. Probably because of the lack of appropriate data at that time, this book, however, did not study the relationship at the aggregate level in developing countries. This article aims at filling the gap by examining country-level rates at two points in time and by analysing, in a multivariate fashion, the determinants of the fertility transition onset and pace in small geographic units in Costa Rica-a less developed country with a relatively long history of both child mortality and fertility decline.