Real-world effectiveness, method by method
The figure that matters is not the one in the leaflet. Leaflets give effectiveness in perfect use: a pill taken every day at the same hour, a condom put on correctly every time. The column below gives typical use — pregnancies observed in a hundred people over a year, missed pills and accidents included. The gap is striking for anything that depends on you: 0.3% in perfect use for the pill, 7% in real life.
| Method | Pregnancies in a year, typical use | Duration | Hormones |
|---|---|---|---|
| Implant | 0.1% | 3 years | yes |
| Hormonal coil | 0.1 to 0.4% | 5 to 8 years | yes |
| Vasectomy | 0.15% | permanent | no |
| Tubal occlusion | 0.5% | permanent | no |
| Copper coil | 0.8% | 5 to 10 years | no |
| Three-monthly injection | 4% | 3 months | yes |
| Pill, patch, ring | 7% | daily to monthly | yes |
| External condom | 13% | every act | no |
| Diaphragm with spermicide | 17% | every act | no |
| Withdrawal | 20% | every act | no |
| Internal condom | 21% | every act | no |
| Fertility awareness | 2 to 23% | daily | no |
| No method | 85% | — | — |
Two ways to read this table. First: long-acting methods dominate, not because they are better designed but because they take human error out of the equation. Second: the condom is the least effective of the common methods and the only one that protects against infection. Both are true at once, which is why so many couples use two methods together.
The contraindications that actually change the answer
Most received ideas about hormones do not hold up. A few situations, however, do rule out combined methods — the ones containing oestrogen, meaning the combined pill, the patch and the ring: migraine with aura, a previous clot or embolism, poorly controlled high blood pressure, smoking over 35, breast cancer, severe liver disease, and the first weeks after giving birth.
None of these rules out contraception altogether: the coil, the implant and progestogen-only methods remain available. That is why the questionnaire asks about it before anything else.