For nearly three decades men and women have increasingly gained the opportunity to control their childbearing with modern contraceptive technologies. In the early 1960s when oral hormonal contraceptives and intrauterine devices first became publicly available in the United States and Europe, the total fertility rate (TFR) in industrialized countries was about 2·7 implying that two-thirds of childbearing couples, some 87 million, were practising contraception. By comparison, in the developing areas, the TFR was 6·1 and only 18% (60 million couples) were contraceptive users. Thirty years later, estimating for 1990, the number of eligible couples practising contraception in the more developed countries (MDCs) is expected to have increased by half, while in the less developed countries (LDCs) the increase is likely to be six times, suggesting as many as 344 million users. Another way to demonstrate the significance of this trend is with a different statistic—that the level of contraceptive use in LDCs in 1990 will exceed half of all couples of childbearing age and be only ten percentage points below the MDC level of 25–30 years ago.

Because of the importance of contraceptive behaviour in most societies today a better understanding is needed of the social and behavioural factors affecting contraceptive decisions and choices of individuals and couples. This paper examines the need for longitudinal, theoretically-based studies of contraceptive use dynamics, including the timing, duration and interaction of reproductive events which may be more important than contraceptive technology in the social, cultural and economic context of fertility control. New research methods and appropriate analysis of data are relevant. Consideration of the social context is essential for the formulation and implementation of effective policies relating to the provision of contraceptive services.

Dynamic models of contraceptive use fill a theoretical gap. They bring behavioural content to the mathematically elegant Markov models of family building. They meet the criterion that Bulatao (1989) advances that method use, discontinuation and switching be considered not in isolation, but with reference to individual reproductive goals. Dynamic models help to link the literature on method choice with the literature on method effectiveness. These theoretical advantages are, at present, counter-balanced by empirical limitations. This article explores the theoretical and empirical underpinnings of dynamic contraceptive choice models.

The determinants of contraceptive method choice in Sri Lanka are examined during a period in which contraceptive prevalence increased by over 60% and involved substantial use of sterilization and traditional methods. Data are from the 1975 World Fertility and 1982 Contraceptive Prevalence Surveys. Polytomous logistic regression is used to model four current contraceptive choices: non-use, use of a traditional method, use of a modern temporary method and use of sterilization. The analysis shows, in 1975 and 1982, strong socioeconomic as well as demographic effects on whether any method is used. However, in both years the type of method chosen is primarily a function of demographic considerations related to the couple's family-building stage rather than social status, implying that in Sri Lanka there are few socioeconomic barriers limiting access to different contraceptive methods. The family planning programme, however, has emphasized sterilization rather than birth spacing methods.

Contraceptive use and method mix were analysed using Philippines national survey data of 1973, 1978, and 1983. The analyses suggest that the reported decline in contraceptive prevalence between 1978 and 1983 was due to under-reporting of use in 1973 and 1983. The shifts in contraceptive method mix were also partly from under-reporting of rhythm and other methods in 1973 and 1983. Nevertheless, the determinants of method choice were similar in all three sets of data. Filipino couples were making rational choices in terms of their contraceptive goals, access, evaluation, and competence. Modifications in the directions and magnitude of the relationships in determining method choice also occurred, partly reflecting the increased use of sterilization by older, higher parity women.

Contraceptive prevalence rates and estimates of continuation rates are derived from unique longitudinal data on post-partum behaviour collected in the Cebu region of the Philippines. Continuation rates vary by base-line and time-varying socioeconomic characteristics for certain contraceptive methods and for using no contraception. Calendar rhythm users have a much lower relative continuation rate than has been found in cross-sectional samples. For women who use a contraceptive method, breast-feeding does not appear to influence contraceptive continuation, but for those who use no methods, breast-feeding appears to substitute for other forms of contraception. Profiles by socioeconomic characteristics of those who continue to use each type of contraceptive method and who use no method could be used to direct family planning programmes towards population sub-groups. The results suggest that for women wishing to postpone a pregnancy, a family planning programme aimed at the young and less educated could effectively increase contraceptive use and continuation.

Several new concepts are used to describe contraceptive use histories for nearly 1200 women in Peninsular Malaysia. These histories are summarized by 81 episode histories. Transition matrices provide useful summaries of the changes women make in their contraceptive practice from one pregnancy interval to the next. Data from the mid-1940s to mid-1970s, during which period there was a dramatic increase in contraceptive use, reveal considerable inertia in individual couples' contraceptive practice. Persistence with a method was greater the less effective the method: while 86% of couples using no method in one interval used no method in the next, only 56% of couples using the pill in one interval also used it in the next. Virtually all transitions are of three types: continuation with the same method, a change from no method to some method, or a change from some method to no method. For only 1% of all pregnancies did couples use one contraceptive method before a pregnancy and a different method after the pregnancy. Differences are examined by calendar year and education.

This study examines contraceptive method switching among married women in the US. It enquires first into the effect of method type and women's socioeconomic characteristics on the risk of switching to each of six methods, including no method, and secondly into the previous methods used by women who adopt specific contraceptive means. The results indicate a great deal of circulation among all method types and of movement to unprotected intercourse. The adoption of sterilization is greatest among women not previously using any contraceptive method.

Patterns of contraceptive method change and their association with reproductive motivation and contraceptive failure are examined using data from a 1986 survey of family planning behaviour of rural Sinhalese married women aged 15–44 in seventeen districts of Sri Lanka. A notable degree of rationality in contraceptive method changes occurs with family formation. The attempt to control unwanted fertility leads to more efficacious use of contraception, including traditional methods. Some methodological improvements to the analysis of contraceptive switching are indicated. Implications of the findings for programmatic emphasis on permanent versus non-permanent modern methods are discussed.