1998d-125 africa birthcontrol congresses contraception contraceptiveagents contraceptivedrugs contraceptives educationalstatus familyplanningservices female handbooks internalmedicine manuals medical medicalpracticemanagement methods practicemanagement research socioeconomicfactors standards sub-saharan therapeuticuse trends unitedstates utilization wp630c761951998 wp640b887c1979 wp640d4891990