Research Methodology / Contraception / Behavior / Culture / Developing Countries / China / Adolescent / Human / Knowledge / Cross-Cultural Comparison / South Africa / Population / Humans / Comparative studies / Female / Male / Attitudes / Great Britain / Middle Aged / Developed Countries / Questionnaires / Human reproduction / Adult / Spermatozoa / China / Adolescent / Human / Knowledge / Cross-Cultural Comparison / South Africa / Population / Humans / Comparative studies / Female / Male / Attitudes / Great Britain / Middle Aged / Developed Countries / Questionnaires / Human reproduction / Adult / Spermatozoa