The poor as a "perfect contraceptive population" and zero population growth.
D000328:Adult; D001741:Black or African American; D001723:Birth Rate; D003267:Contraception; D005006:Ethnicity; D005193:Family Planning Services; D005260:Female; D005298:Fertility; D006801:Humans; D007182:Income; D011158:Population Growth; D011203:Poverty; D011247:Pregnancy; D011275:Pregnancy, Unwanted; D014481:United States; D014798:Vital Statistics