The level of unmet need in a country is not static but always in flux, depending on the interplay of two factors fertility desires and contraceptive use. Thus a high level of unmet need does not necessarily indicate program failure, nor does a low level necessarily indicate success. Most countries follow a similar pattern as they move through the demographic transition from high to low fertility. At first there is neither much contraceptive use nor much unmet need because most couples do not want to, or are unaware that they can, limit or space births.
Fertility is high.
As more couples want to control their fertility, unmet need rises because attitudes change faster than contraceptive use rises. Contraceptive use begins to rise as well, however, and the fertility rate starts to decline. Reproductive attitudes continue to change and, as information and services respond to people's changing attitudes, contraceptive use rises rapidly, while unmet need declines. Fertility often declines rapidly. Finally, most women do not want more children, and use of family planning is widespread.