The more contraceptive methods that women know, the lower their level of unmet need, as DHS findings illustrate (19) (see Figure 4). In the Dominican Republic, for example, among women who know three methods or fewer, unmet need is more than twice as high, at 35%, as among women who know six methods or more, at 14%. A study using DHS data from Egypt and controlling for the effect of other factors on contraceptive use found that women who knew of more contraceptive methods were less likely to have unmet need (18).

Whether or not a woman knows of just one contraceptive method makes little difference to unmet need, however. In most countries outside sub-Saharan Africa, a large majority of people are aware of at least one contraceptive method—not only contraceptive users but also women with an unmet need (37). As might be expected, lack of awareness of any contraceptive method is most likely to explain unmet need in countries with little contraceptive use, as in sub-Saharan Africa (237). This is because, if a woman does not know about contraception itself, she cannot cite other reasons for not using it, such as lack of availability or side effects.

Just knowing that methods exist may not be enough information for many women. In-depth studies show that many women may be aware of at least one, and often several, contraceptive methods, but they often do not know how the methods work, what their side effects are, how to obtain them, how much they cost, whether their use can be kept private, and other aspects that may affect the decision to use contraception (35). Even when women give interviewers such reasons for nonuse as dislike of contraception, fear of side effects, or belief that they cannot get pregnant, these reasons suggest a lack of information about reproduction and contraception (98). In interviews and focus-group discussions, many women who are not using family planning "seem overwhelmed, and therefore demoralized, by what they do not know about contraception" (35).

Along with other reasons, lack of sufficient knowledge may contribute to more than two-thirds of all unmet need, Bongaarts and Bruce have estimated from DHS data for 12 countries (25). The researchers created a "knowledge index" consisting of three items: (1) mentioning a modern contraceptive method without being prompted; (2) being aware of its source; and (3) having an opinion about its side effects. In general, the level of unmet need is lower in countries where this knowledge index is higher. In five of the six sub-Saharan countries studied and in Peru, fewer than half of women with an unmet need could mention even one method, identify its source, and discuss its side effects (25).

Knowledge of availability. To use contraception, women must not only know about the existence of contraception itself but also what services are offered where and when. Studies have shown that the more women find contraception to be available, the more likely they are to use it (51, 147, 215). In general, women with an unmet need perceive family planning services to be less accessible than do contraceptive users, according to DHS data (19). WFS data for Nepal in 1979 showed that the level of unmet need for limiting in Nepal was lower among women who knew of a nearby service delivery outlet than among those who knew only a distant outlet (175). Similarly, in South Korea in 1974, 85% of women who did not know where to obtain contraceptives had unmet need. By comparison, 45% of women who said that they knew a source had unmet need. Perceived availability was more important to the level of unmet need than was women's education or residence (210).