A history of the measurement of unintended pregnancies and births.

OBJECTIVES: This article reviews the history of the measurement of unwanted and unintended pregnancy in fertility surveys in the United States. These concepts were developed in order to help explain trends and differences in birth rates in the United States. BACKGROUND: Unwanted fertility was first measured systematically in a survey in Indianapolis in 1941. The first national surveys to measure the concept of unwanted fertility were the 1955 and 1960 Growth of American Families Studies. All three of these surveys were limited to married women. In the 1965 National Fertility Survey, the concept of mistimed births was introduced. The 1973, 1976, 1982, and 1988 National Survey of Family Growth (NSFG) continued to measure trends in unwanted and mistimed fertility, while expanding the population interviewed, from currently married to all marital statuses. The 1993 and 2001 NSFGs have enriched the data on wantedness with new measures of ambivalence and the strength of feelings about having children. CONCLUSION: Measures of unwanted fertility, while imperfect, have been useful and will continue to be improved in the future.