2006h-739 2009h-223 20thcentury 21stcentury birthcontrol birthrate china colonies conservationofnaturalresources contraception contraceptives demography developingcountries environmentalaspects familyplanningservices governmentpolicy hb881c7371975 history hq766 imperialism internationality jv1018i882013 liberty population populationdensity populationpolicy publicpolicy racerelations reproductivehealthservices reproductiverights