Unmet need is defined on the basis of women's responses to survey questions. Essentially, women who respond that they want to postpone or avoid childbearing and also report that they are not using contraception (including use by their partners) are defined as having an unmet need. Since 1984 the main information source for measuring unmet need has been the Demographic and Health Surveys (DHS). These surveys have collected comparable information on fertility and family planning in more than 50 developing countries through interviews with representative samples of women and, recently in some countries, of men as well (174).

In addition, the Family Planning and Reproductive Health Surveys (FP/RHS) have estimated unmet need in national surveys since 1985. While the FP/RHS formulation of unmet need is not strictly comparable with that used in the DHS, these surveys provide estimates of unmet need for some countries, principally in Latin America and the Caribbean, that have not been surveyed in the DHS (174).

Standard formulation of unmet need. The formulation of unmet need that has become the standard and is used most widely to measure unmet need was developed principally by Charles Westoff (see How the Unmet Need Concept Evolved). In this formulation the unmet need group includes all fecund women who are married or living in union—and thus presumed to be sexually active—who are not using any method of contraception and who either do not want to have any more children or want to postpone their next birth for at least two more years. Those who want to have no more children are considered to have an unmet need for limiting births, while those who want more children but not for at least two more years are considered to have an unmet need for spacing births.

The unmet need group also includes all pregnant married women whose pregnancies are unwanted or mis- timed and who became pregnant because they were not using contraception. Similarly, women who recently have given birth but are not yet at risk of becoming pregnant because they are amenorrheic postpartum are considered to have an unmet need if their pregnancies were unintended (234, 237, 238) (see Figure 1).

In DHS conducted since 1990, pregnant or amenorrheic women are considered to have an unmet need for limiting births only if they respond that their current pregnancy or recent birth was unintended and that they do not want to have any more children (237). This is a change from earlier DHS, made necessary because, in the version of the questionnaire used since 1990, many women, particularly in sub-Saharan Africa, indicated that they did not want more children but were pregnant or amenorrheic, but they also responded to another question that they wanted another child. This apparent discrepancy probably is due to ambiguous wording of the questionnaire (237). Women who give such apparently conflicting responses now are classified as having unmet need for spacing births.

In the standard formulation the unmet need group does not include pregnant or amenorrheic women whose current pregnancy or recent birth was intended, even if they do not want to become pregnant again right away. Also, women who became pregnant unintentionally because of contraceptive method failure are not considered to have an unmet need for family planning in general, although they may need more reliable contraception (238).

Expanded formulations. As Ruth Dixon-Mueller and Adrienne Germain have pointed out, the standard formulation does not identify the full extent of need for family planning (55, 56). The standard formulation may be taken to suggest that all women using any contraception, whether effective or ineffective, appropriate or inappropriate, have their contraceptive needs met. In fact, however, some contraceptive users could be considered to have an unmet need if they are using an ineffective method, using a method incorrectly, or using a method that is unsafe or unsuitable for them.

Karen Foreit and colleagues have called this broader formulation the unmet need for "appropriate contraception" (67). For example, contraceptive users may need a more appropriate method because their current method causes side effects or because they are using a method best suited to spacing births when in fact they want no more children (55).

In countries where many women use traditional methods of contraception, it may be more appropriate to define unmet need as including women using traditional methods, such as periodic abstinence and withdrawal, in addition to those using no method at all (27, 50, 132, 193). This is because contraceptive failure rates usually are particularly high for traditional methods (180). In countries where the prevalence of traditional method use is high, the FP/RHS include an expanded measure—"need for any or more effective contraceptive methods"—as well as a measure of unmet need for any contraceptive method (79, 101, 132, 192).

Others with unmet need. The standard formulation does not consider unmet need among unmarried women, including unmarried young adults, who are sexually active and at risk of unintended pregnancy. Because there probably is much unmet need among unmarried sexually active women, this is a serious limitation, as Westoff has observed (229). When only women who are married or living in union, rather than all sexually active women, are considered as the basis for measuring unmet need, the implication may be that other women do not need contraception (55). In fact, the level of unmet need among sexually active unmarried women may be higher than among married women. Sexually active, unmarried women—including not only the never-married but also the separated, divorced, and widowed—typically have an even greater stake in avoiding pregnancy than do married women, but in many countries they are less likely to use contraception (237).

While there is no generally agreed-upon concept of unmet need among men comparable to that among women, surveys could provide the basis for such a formulation (233). In the FP/RHS, for example, men are considered to have an unmet need if they are sexually active, their partners are fecund and not pregnant, and they do not want their partners to become pregnant, but neither they nor their partners use contraception (127, 132).

Assessing unmet need among young adults is particularly important. Family planning and other reproductive health care programs reach relatively few unmarried young adults, women or men (125, 134, 246). While in most countries only a minority of young adults engage in sexual activity before marriage (125), most who are sexually active have a clear need for contraception (25,55, 134, 237).

Reflecting recommendations in the Programme of Action of the International Conference on Population and Development (ICPD), Cairo, 1994, Steven Sinding and Mahmoud Fathalla have suggested conducting "a new generation" of surveys that measure unmet need more broadly, including unmet need among people who already are using contraception but may be dissatisfied with their method (200). Such surveys would gather both quantitative and qualitative information about women's and men's reproductive intentions and contraceptive use, experience with side effects, discontinuation of contraceptive use, and other problems related to family planning. Such information could help extend the focus of unmet need from use of any contraception to the quality of care (200).