The rise in contraceptive use, generally from negligible levels, throughout much of the Third World during the last two decades represents one of the most fundamental social changes of our times having a major impact on both fertility levels and patterns of reproductive behavior. The basic contours of this phenomenon are apparent from the levels of contraceptive prevalence derived from the various so-called KAP surveys (of knowledge, attitude and practice relating to family planning) conducted earlier and more recently from the two large-scale international survey projects known as the World Fertility Survey (WFS) and the Contraceptive Prevalence Survey (CPS). As a recent review of these two major projects has indicated, however, surprisingly little effort beyond documenting levels of use has gone into analyzing the anatomy of this remarkable change in contraceptive prevalence (Cleland, 1986).

One of the aspects of contraceptive use that has received relatively little attention is the process of contraceptive initiation, both in terms of first post-marital use and in terms of initiation of particular episodes, and how the pattern of initiation changes with rising level of overall use. The present study focuses on contraceptive initiation in Thailand where, in the course of the last two decades, contraceptive use rose from 15 to 68 percent among currently married women aged 15-44 and fertility levels fell by well over half (Chayovan, Kamnuansilpa and Knodel, 1988; Knodcl, Chamratrithirong and Debavalya, 1987; Knodel, Chayovan, and Frisen, 1988). More specifically, this study examines the pattern of first post-marital contraceptive use in relation to the stage of family building, with particular attention to use before the first pregnancy, and the initiation of contraceptive use following childbirth, with particular attention to the timing of initiation relative to the immediate postpartum period and the return of menses.