Descriptions of studies included in the effectiveness review
| Study | Location | Population | Sampling | Study design |
| 2006–2008 Border Contraceptive Access Study10 12 13 | El Paso, Texas, USA | 1046°C users aged 18–44 who obtained OCs either OTC from a Mexican pharmacy (n=532) or from a family planning clinic in El Paso (n=514) | Convenience sampling | Cohort study following both groups of women in four surveys over 9 months |
| 2000 Mexican National Health Survey analysis14 | Nationally representative sample from Mexico | 1195°C users aged 20–49 who obtained OCs either OTC from a pharmacy (n=501) or from a health clinic of some sort (n=694) | Four-stage probability proportionate to size sampling | Cross-sectional study design |
| 1979 Mexico National Fertility and Mortality Study9 | Nationally representative sample from Mexico | 2063°C users aged 15–49 who (when they first used contraception) obtained OCs either OTC from a pharmacy or store (39%) from a private physician or private clinic (17%), or from the national family planning programme (44%) | Stratified probability sample | Cross-sectional study design |
| 1974 Colombian Fertility and Contraceptive Use Survey11 | Bogotá, Colombia | 893°C users aged 15–49 who (when they first used contraception) obtained OCs either OTC from a drugstore or similar commercial outlet without a medical prescription and without the advice of a physician or an organised family planning programme (n=298) or chose OCs as her first contraceptive method through a physician or family planning programme (n=595) | Three-stage probability sample | Cross-sectional study design |
OC, oral contraceptive; OTC, over the counter.