Westoff C F
Office of Population Research, Princeton University.
Fam Plann Perspect. 1988 Jan-Feb;20(1):4-13.
Based on data from the 1982 National Survey of Family Growth, exposure to the risk of unintended pregnancy is classified by use of specific contraceptive methods and by nonuse, and average rates of unintended pregnancy are estimated for each type of exposure. Three hypothetical models of improved contraceptive practice are then applied to the data for all women and for age, race and marital-status subgroups. The first two models assume increases in the use of some existing contraceptive methods, but only the second model additionally assumes the introduction of new methods. The third model assumes the complete elimination of nonuse of contraception. These models yield different estimates of the reduction in unintended pregnancy rates which are illustrated for various age-groups, for whites and blacks and for married and unmarried women. Among all women aged 15-44, the changes assumed by Model I imply a 32 percent reduction in unintended pregnancy; Model II implies a 56 percent reduction; and Model III implies a 57 percent reduction. The implied reductions in abortion are in a similar range.
根据1982年全国家庭增长调查的数据，意外怀孕风险的暴露情况按使用特定避孕方法和未使用避孕方法进行分类，并针对每种暴露类型估算意外怀孕的平均发生率。然后，将三种改进避孕措施的假设模型应用于所有女性以及按年龄、种族和婚姻状况划分的亚组数据。前两个模型假设某些现有避孕方法的使用有所增加，但只有第二个模型还假设引入了新方法。第三个模型假设完全消除未使用避孕措施的情况。这些模型对意外怀孕率降低幅度的估计各不相同，针对不同年龄组、白人和黑人以及已婚和未婚女性进行了说明。在所有15至44岁的女性中，模型I假设的变化意味着意外怀孕率降低32%；模型II意味着降低56%；模型III意味着降低57%。堕胎率的隐含降低幅度也在类似范围内。
