This article of the past and current measures of unintendedness of pregnancy has been offered in the hope that investigation into this area can be expanded. Current information available from available national surveys is not comparable due to different survey questions, inclusion criteria, and timing of interviews. What are often reported as rates of unintendedness may be rates of unwantedness--a completely different concept. Many studies fail to delineate the distinction between those unintended pregnancies that are indeed unintended versus those that were mistimed. Potentially, these existing data sets could be reanalyzed by using specific inclusion criteria for unintendedness, maternal age, and marital status. This information might be helpful in improving the comparability between the surveys and in assessing trends in unintendedness. In the future, to accurately measure unintendedness of pregnancy, we must use a consistent definition that takes into account the complexities of the issue. Valid and reliable scales that reflect the value of unintendedness from the mother's perspective need to be developed to reflect the potential change in intendedness over time. The adequate measurement of unintendedness of pregnancy is the first step in addressing the Healthy People 2000 goal and measuring progress in addressing the nation's reportedly high rate in the long-term goal of addressing the risk factors of unintended pregnancy.