Contraceptive prevalence levels and trends in developing countries have long been a focus for family planning and population researchers. An understanding of trends in contraceptive prevalence, both overall and for particular methods, is important for donors involved in providing contraceptive commodities to large family planning programs and for in-country managers of these programs.

Availability of contraceptive methods within national family planning delivery systems is clearly a key determinant of prevalence and method choice. The types of delivery systems available to programs may be influenced by major policy decisions made by top-level program managers; within programs, modes of delivery may be determined by the numbers and types of service delivery points and by the skills and biases of staff.¹

These and other program characteristics interact with social, cultural, economic and physiologic circumstances to affect overall contraceptive use and use of particular methods. However, no program can operate optimally unless it is able to procure and distribute adequate quantities of desired and appropriate methods² to meet the demand when a population is growing and an increasing proportion of men and women wish to practice contraception.

The research upon which this article is based was prompted by concerns about supply imbalances expressed by the U.S. Agency for International Development (USAID). USAID, which has long been the largest donor of contraceptives to developing countries, has been joined by other major donors in its concern about the validity of annual national contraceptive forecasts on which these donors must base procurement and supply decisions. Often, these concerns have stemmed from supply underestimates and consequent shortages of contraceptives. At other times, they have emerged when supplies of contraceptives have considerably exceeded subsequent demand, resulting in overstocking and sometimes expiration of dated commodities.

Projections of country programs' contraceptive requirements are sometimes based on long-term demographic goals and desired levels of use, with little attention to the program infrastructure required to meet these objectives. Consequently, the utility of such projections is limited. Shorter term forecasts are intended to reflect both contraceptive needs and the capacity of public- and private-sector distribution systems to meet these needs. Too often, however, little effort is made to assess the validity of such projections by comparing them with international trends and other countries' experience.

Our intent here is to utilize individual country surveys, aggregated by region, to present data on annual changes in overall and method-specific prevalence, upon which more realistic contraceptive forecasts may be based. While other work has also focused on trends in contraceptive prevalence in less developed countries³ our purpose here is to examine these trends and their implications from the standpoint of family planning program managers and donors.

Methodology

Our data are derived mainly from Demographic and Health Surveys (DHS), World Fertility Surveys and Contraceptive Prevalence Surveys conducted between 1974 and 1992 in 35 developing countries.⁴ For each country, we used at least two surveys, conducted a minimum of two years apart, that provided measures of total and method-specific prevalence. (For Brazil, where no national survey was available before 1986, we examined four regions, comparing data from earlier state or regional family planning and maternal and child health surveys with similar later surveys or with the 1986 DHS survey results for those regions.) Table 1 lists the years covered by the 106 surveys that met these criteria.*

While other reports have presented prevalence estimates weighted in terms of population size,⁵ we have elected to give all countries equal weight with respect to population size, because our focus is on prevalence change as a function of country-based programs. Thus, we are equally interested in the patterns observed in a small population (for example, Jamaica) and in a larger population (such as Bangladesh or Nigeria). However, to give proportionately greater weight to rates of change in prevalence observed over longer time periods, our computations of annual aggregate rates of change incorporate weights equal to the number of years between surveys. This weighting reduces the proportion of observed variance attributable to random variation relative to underlying secular trends.^†

Two measures are used to describe trends in contraceptive prevalence. The first, the annual percentage-point change, is a linear interpolation of prevalence at the initial and final survey dates. It is simply the difference in prevalence between the two time-points, divided by the number of years elapsed between surveys. For regional and total computations of this measure, we have summed the difference in prevalence between the initial and later surveys, and divided the result by the sum of the years between surveys. (Individual country rates, which could be unduly sensitive to the use of complete years rather than fractional years between surveys, are not given.) We note that the method of aggregation for computing regional rates minimizes the effects of some intersurvey intervals' being more or less than complete years.

Our second measure is the stepwise annual rate of change, or the exponential change that would be required to move in annual increments from the initial to the final year's prevalence.^‡ This measure can be thought of as the annually compounded rate of change that must be applied to the initially observed prevalence to attain the level observed at the subsequent survey. The intersurvey rate of change is more sensitive than the annual percentage-point change to small absolute changes in program activities when programs are in their early stages and initial prevalence is still very low. The regional and overall rates of change are composed of the average of the rates of change of the individual countries, weighted by the number of years between surveys; we computed these rates by summing the products of the individual rates of change and the years between surveys, and dividing the result by the sum of the years between surveys.

While the absolute change in prevalence is the better-known of these measures, the stepwise annual rate of change is more useful for donors and managers who must plan for program expansion at early program stages. At the higher levels of prevalence typical of mature programs, the sheer growth of the eligible population becomes a major determinant of increases in supply requirements. This factor is much less important in "young" programs with large proportions of women in need of contraception, where program growth can far outpace the growth of the eligible population. Simply put, once the initial transport, storage and distribution procedures for contraceptives are established in a given area, an increase in contraceptive demand due to population growth can be more easily accommodated.

In our analyses, we distinguish between traditional and modern methods. Traditional methods are periodic abstinence, withdrawal and douche. Modern methods are male and female sterilization (although the great majority of procedures are female), oral contraceptives, IUDs, injectables, condoms and other barrier methods. We refer to all modern contraceptives other than sterilization as supply-based methods; from an overall program perspective, whether these methods require consistent resupply (as is the case with condoms and oral contraceptives) or are long-acting (injectables and IUDs), their effectiveness depends upon their uninterrupted availability to clients.

The annual absolute change for traditional and modern methods does not always add up exactly to the annual absolute change for all methods, since folk methods were classified in some surveys as "other" and in some as traditional. Because of the definitional inconsistencies among surveys regarding traditional methods, we focus on modern methods, although we present summary data for traditional methods in the tables.

Results

Total Intersurvey Change

To provide a summary measure of contraceptive prevalence trends by region, we used data from the first and the most recent surveys in each country to calculate mean prevalence for modern and traditional methods and for individual methods. As Table 2 shows, total prevalence increased between surveys by at least 10 percentage points in all regions except Sub-Saharan Africa; Asia showed the greatest absolute increase, from 25% at the initial survey to 45% at the final survey. The prevalence of modern method use also increased most for Asia (18 points) and least for Sub-Saharan Africa (six points). Traditional method use showed little net change, increasing very slightly in Asia and in North Africa and the Middle East, and decreasing very slightly in the other regions examined.

The most substantial growth in method-specific prevalence between the initial and final survey years (eight percentage points overall) occurred for sterilization (see Table 3); the increases were especially large in Asia (14 points) and Latin America and the Caribbean (nine points). Indeed, consistent with findings from other studies,⁶ sterilization has become the leading contraceptive method overall (with a prevalence of 13%, compared with 12% for the pill and 3-6% for the IUD and condom). However, reliance on sterilization still trails oral contraceptive use in Sub-Saharan Africa, and lags behind both pill and IUD prevalence in North Africa and the Middle East.

Increases in the prevalence of pill and IUD use amounted to 1-2 percentage points overall and were generally less than three points in each region. The exception was that IUD prevalence grew by nine percentage points in North Africa and the Middle East. Condom use showed negligible change. =subhead

Annual Rates of Change

While considerable variability is evident among countries, the great majority showed marked increases in total prevalence; a few exhibited little intersurvey change.^§ Haiti, with a sharp drop in reported prevalence, was a notable exception to the general pattern. In 30 of the 33 countries for which both measures could be calculated, the prevalence of sterilization grew at a substantially faster rate than that of other modern methods.

The annual percentage-point change in total contraceptive use was greatest for Asia (1.8 points; see Table 4); in descending order, the absolute changes in North Africa and the Middle East, Latin America and the Caribbean, and Sub-Saharan Africa followed. In each region, however, the annual rate of change in the prevalence of modern method use was larger than the rate of change for all methods combined, underscoring that most of the increase in total contraceptive prevalence was due to the increase in use of modern methods.** For the annual rate of change, Sub-Saharan Africa headed the list (9%); the other regions maintained their sequence, with 3-7% increases. It was not surprising that Sub-Saharan Africa had the largest rate of change, since initial prevalence was so much lower there than in the other regions.

Data on specific methods (Table 5) show that the greatest growth in prevalence was for sterilization, which gained one percentage point each year. Oral contraceptive, IUD and condom prevalence levels increased only slightly. The use of sterilization increased particularly rapidly in Asia and in Latin America and the Caribbean, where prevalence grew by slightly more than one percentage point annually. In the other regions, by contrast, the absolute increase was only a fraction of a point.

Sub-Saharan Africa had by far the largest annual rate of increase in sterilization prevalence (21%); notable gains also occurred in Asia (14%) and Latin America and the Caribbean (9%). In North Africa and the Middle East, where policymakers, service providers and couples may offer greater resistance to the use of permanent contraception, sterilization prevalence grew by only 5% annually.

Annual absolute increases in the use of orals, IUDs and condoms were much smaller—a fraction of a percentage point. Among these methods, the annual absolute increase was greatest for IUDs (0.24 percentage points); however, this growth varied by region. The annual rate of change was greatest for IUDs as well (4%). IUD prevalence made the largest gains in North Africa and the Middle East. It also grew in Latin America and the Caribbean and in Sub-Saharan Africa, but decreased slightly in Asia. These trends held for both measures.

Sub-Saharan Africa had the greatest increase in oral contraceptive use, followed by Asia and North Africa and the Middle East. In Latin America, the prevalence of pill use hardly changed. As with IUDs, these trends held for both the absolute change and the annual rate of change.

Condoms, which account for a disproportionate share of donors' commodity budgets, particularly relative to the couple-years of protection they provide, are the method most advocated and used to inhibit the spread of the human immunodeficiency virus (HIV). Condom prevalence increased between surveys, although more slowly than anticipated. The annual absolute change in condom use was negligible, and the annual rate of change was 2%. Condom use grew by about 3% yearly in Asia and in North Africa and the Middle East, but the increase was minuscule in Latin America and the Caribbean. (Condom data for Sub-Saharan Africa are not presented because most of the countries reported a prevalence of less than 1% at both surveys.)

Discussion

These data have several implications for donor agencies and program managers. The fairly slow observed rate of change in prevalence for supply-based methods should lead program managers and forecasters to guard against unrealistically high expectations when estimating likely growth in contraceptive demand. Although these data are not based on a random sample of less developed countries, and the inferences drawn are somewhat speculative, these findings are nonetheless consistent with others reported in the literature.⁷

The question to program managers and to donor agencies alike is how predictive these observed rates are of future contraceptive commodity requirements. Several considerations deserve mention. Both the rising total prevalence and the rapid increase in use of the most effective methods suggest that prevalence has not yet plateaued for any of the modern methods, so further growth is likely. In addition, the base population of women eligible for contraception continues to grow, typically at 2-3% per year, thus providing built-in potential for greater demand for supply-based methods. Furthermore, two additional and very effective supply-based methods, the three-month injectable and the long-acting hormonal implant, may increasingly be substituted for the supply-based methods we have discussed and thus may affect current trends, particularly in the use of oral contraceptives and IUDs.

Whether improved access to injectables and implants will result in greater overall contraceptive use or whether these methods will simply substitute for IUDs, orals, condoms and other contraceptive methods remains to be seen. Within five years, the progestin-only injectable and quite possibly the five-year hormonal implant are likely to account for a substantial proportion of contraceptives donated by USAID.

Regarding condom use trends in the AIDS era, we note that even though data from the most recent national surveys fail to capture any appreciable upsurge in condom use, such changes may have occurred too recently to be reflected in these surveys. Furthermore, since substantial proportions of condom users are unmarried, DHS-type surveys of women in union are not ideal tools for monitoring changes in condom use resulting from concern about HIV transmission. In this case, an examination of condom distribution data may be more indicative of emerging trends.

In a preliminary examination using annual USAID commodities shipment data for 31 countries, we found sizable increases in the number of donor-supplied condoms since 1986. For several countries, particularly in Sub-Saharan Africa, the number of donor-supplied condoms had increased substantially. Among more extreme examples, supplies to Tanzania increased from 500,000 in 1987 to 26.6 million in 1991, after which they leveled off. In Kenya, condom supplies increased from 4.3 million in 1986 to 58.6 million in 1993, and in Zimbabwe, supplies climbed from three million to 21 million between 1986 and 1990, before declining somewhat.

Some of these extreme increases appear to reflect an expansion in the contraceptive distribution network (in part as a response to HIV) and an effort to fill the existing distribution pipeline, rather than a rapid increase in underlying demand. This is suggested by the subsequent leveling off in requested condom supplies and, in some cases, even a decline from these peak levels in countries having experienced the most rapid increases. However, condom donations to Sub-Saharan Africa have increased substantially, from an annual average of 34 million in 1986 and 1987 to an average of 194 million for 1992 and 1993. USAID condom donations to regions other than Sub-Saharan Africa actually declined somewhat during these years, and increased supplies from other donor agencies, such as the World Health Organization, only partly compensated for this decline. Commodity forecasters obviously must attend closely to future HIV trends and to the potential for a corresponding worldwide increase in the demand for condoms.

Despite campaigns to increase contraceptive demand, the trends we have documented indicate that for the most part, changes in prevalence occur rather slowly. We have noted the direct programmatic implication of these results, which caution against unrealistically high forecasts of requirements for supply-based contraceptives in the absence of increased efforts to both stimulate and meet contraceptive demand. The different patterns of method preference among regions suggest the need for culture-specific data about reasons for method preferences, as well as donor programs to meet these preferences or, in some cases, to influence users toward the use of more effective methods,⁸ especially in Sub-Saharan Africa.⁹

Increases in contraceptive prevalence, and particularly in the use of more effective modern methods, are associated with observed declines in fertility. A corollary to this observation is that problems with availability and access to effective contraceptives can hinder reductions in population growth rates and efforts to impede the spread of HIV.

Mauldin and Ross¹⁰ have estimated the levels of contraceptive practice required to achieve alternative population growth rates. For the countries represented in this study, even the United Nations "medium variant" for growth rates will not be achieved with current trends in prevalence. Therefore, to achieve societal goals of fertility reduction and health promotion, national policymakers and program managers must continue to engage in activities aimed at creating demand in both family planning and the prevention of HIV and other sexually transmitted diseases, while simultaneously expanding access to contraceptive methods for underserved populations.=subhead