Contraceptive failure in the United States: estimates from the 1982 National Survey of Family Growth.

A multivariate life-table analysis of national survey data from 1982 indicates that among currently married women, the pill and IUD have the lowest use-failure rates. During the first year of use, about three percent of pill users and six percent of IUD users experience an unintended pregnancy. Failure rates for the remaining methods range from 14 percent for the condom to 22 percent for spermicides; between these lie rhythm and natural family planning (16 percent), the diaphragm (17 percent) and other methods, mainly withdrawal, douche and abstinence. Married women using no contraceptive method experience an unintended pregnancy rate of 40 percent during the first year of unprotected intercourse. A woman's age, pregnancy intention (either to delay or to prevent births), parity and income all have significant effects on the risk of unintended pregnancy. The risk generally declines with age, except for women attempting to prevent an unwanted pregnancy, among whom women under 20 have lower failure rates than do those 20-29 years of age. As expected, women attempting to prevent an unwanted pregnancy have lower failure rates than do those seeking to delay a wanted pregnancy, with the difference being greatest for women under 20 years of age and smallest for 20-29-year-olds. Use-failure rates among low-income women are higher than those among women with larger family incomes, while low-parity women have lower failure rates than do women of higher parity. On average, standardized use-failure rates for single women are lower than those for married women, probably because of a lower average level of intercourse among single women. In addition, these rates are understated because of the substantial underreporting of abortion among single women; if abortion reporting were complete, failure rates would be about 1.4 times as high as they appear here, and thus would be close to those of married women. Differences in the risk of unintended pregnancy among single women show a number of similarities with those seen among married women: Use of the pill and IUD is associated with the lowest failure rates, reliance on the condom is associated with intermediate failure rates, and use of spermicides is linked with the highest failure rates. However, while rhythm and the diaphragm exhibit use-failure rates that are among the highest found for single women, failure rates for these methods are at intermediate levels among married women.(ABSTRACT TRUNCATED AT 400 WORDS)