Ford K
Fam Plann Perspect. 1978 Sep-Oct;10(5):264-9.
The pill and sterilization were the main methods used by U.S. married couples in 1976 to prevent pregnancy. In 1973 the poor were more likely than the more affluent, and blacks as likely as whites, to use the most effective methods. By 1976 this was no longer true, because more blacks turned to traditional and folk methods and the sterilization increase was largely limited to more affluent whites.
1976年，避孕药和绝育是美国已婚夫妇避孕的主要方式。1973年，穷人比富人更有可能，黑人与白人可能性相当，采用最有效的避孕方式。到1976年，情况不再如此，因为更多黑人转向传统和民间避孕方法，绝育人数的增加主要限于较富裕的白人。
