Contraceptive failure in the United States.

Data obtained from the 1970 National Fertility Study are analyzed to determine the incidence of contraceptive failure according to intent, social background, and method. Analyzed by life-table procedures, the data indicate that 40% of contraceptive users fail to achieve their goal of either delaying (26%) or preventing (14%) pregnancy. Those women who are relatively young at the beginning of their exposure to risk are much more likely to fail than older women. Pregnancy order and educational attainment do not affect contraceptive failure rates when intent and age are held constant. Blacks are much less successful than whites in delaying and preventing pregnancy, and white Catholics are less successful in delaying, but just as successful in preventing pregnancy as white non-Catholics. Attempts to prevent or delay pregnancy were much more successful in 1970 than 1955, partially because of the use of oral contraceptives, but also because of greater care taken no matter which method was used. Failure rates by method with intent and age constant are as follows: pill--6%, IUD--12%, condom--18%, diaphragm--23%, foam--31%, rhythm--33%, and douche--39%. These figures reflect the characteristics of those who use each method as well as the method itself. Methodological problems with this analysis are discussed along with their implications.