Unlike previous generations, which did not have direct and instant access through the mass media to the rest of the world, most couples today are exposed constantly to new ideas. These "ideational factors," as well as economic and social changes, have led a growing number of couples to want smaller families and to use modern contraception to achieve that goal (25).

The potential for fertility declines in developing countries has been underestimated because many studies have neglected the impact of the rapid diffusion of ideas (44 ). "Interest in smaller families and in family limitation does not necessarily appear suddenly as an unambiguous rational decision of large masses of people," Ronald Freedman and Deborah Freedman have observed (48). Rather, interest in family planning spreads from one socioeconomic group to the next and from the cities to the rural areas throughout a country, depending on available communication channels. These patterns suggest the importance of mass media and communication campaigns in speeding the diffusion of new attitudes about reproduction and thus in speeding the adoption of contraception.