Efficacy is about typical use
Perfect-use figures mislead. What matters clinically:
| Method | Typical-use failure per year |
|---|---|
| Implant | < 0.1% |
| IUD (copper or hormonal) | < 1% |
| Injectable (depot medroxyprogesterone) | ~4% |
| Combined pill, patch, ring | ~7% |
| Male condom | ~13% |
| Withdrawal, fertility awareness | 18–24% |
The gap between the implant/IUD and the pill is entirely about adherence, which is why long-acting reversible contraception is first-line for most people, including adolescents and those who have never given birth.
Absolute contraindications to oestrogen
Learn these as a block — a stem usually contains exactly one:
- Migraine with aura, at any age
- Age ≥ 35 and smoking ≥ 15 cigarettes/day
- History of VTE, or known thrombophilia
- Known ischaemic heart disease or stroke
- Blood pressure ≥ 160/100
- Current breast cancer
- Active liver disease, or liver tumours
- Complicated valvular disease, prolonged immobilisation, major surgery
- < 21 days postpartum, or < 6 weeks if breastfeeding with other risk factors
- Diabetes with vascular complications, or duration over 20 years
- Systemic lupus erythematosus with antiphospholipid antibodies
None of these applies to progestin-only methods or the copper IUD, which is why those are the answer when oestrogen is out.
Non-contraceptive benefits worth mentioning
- Combined pills: lighter, more predictable periods; less dysmenorrhoea; acne improvement; and a durable reduction in ovarian and endometrial cancer risk
- Hormonal IUD: markedly lighter bleeding — a treatment for menorrhagia in its own right, and used for endometrial protection with oestrogen therapy
- Depot injection: amenorrhoea; but causes reversible bone density loss and delayed return of fertility
Emergency contraception
In order of effectiveness:
- Copper IUD — most effective by a wide margin (> 99%), inserted up to 5 days after intercourse or after the estimated ovulation, and it continues as ongoing contraception
- Ulipristal acetate — up to 5 days, more effective than levonorgestrel, especially closer to ovulation and at higher BMI
- Levonorgestrel 1.5 mg — up to 72 hours, declining effectiveness with time
Neither oral method disrupts an established pregnancy. Ulipristal and progestins interact: delay starting or restarting hormonal contraception for 5 days after ulipristal.
Always paired with
Condoms for STI protection — no hormonal method or IUD provides any. And screening for chlamydia and gonorrhoea in those under 25 or at risk, which is a natural part of the same consultation.