In this paper we shall try to present a simple mathematical model for describing the adaptation to new forms of behavior and for studying the subsequent generalization of these forms among populations ...

BACKGROUND Extensive research in both developed and developing countries has shown that preferences and intentions for future childbearing predict behavior. However, very little of this research has ...

contraceptive use, early and nearly universal marriage practices, and high fertility preferences. Less than 20% of married women between age 15-49 (ranging from 18% in Burundi to 5% in Chad) use a ...

Wealthy countries all over the world are struggling with historically low birth rates—a new study has looked at why this is the case and has a slightly different answer to what research has said ...

NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of ...