Expansion
Suppress ovulation, thicken mucus, or prevent implantation
Expansion
| Method | Main mechanism |
|---|---|
| Combined hormonal | Suppresses ovulation by inhibiting the LH surge; also thickens mucus and thins endometrium |
| Progestogen-only pill | Thickens cervical mucus; ovulation inhibited in only some users (desogestrel inhibits it in most) |
| Injectable and implant | Inhibit ovulation plus mucus effects |
| Levonorgestrel intrauterine system | Endometrial atrophy and mucus thickening |
| Copper intrauterine device | Copper is toxic to sperm and ova; also prevents implantation |
| Barrier | Physical prevention |
Emergency contraception
- Levonorgestrel: delays or inhibits ovulation; less effective once the LH surge has begun. Within 72 hours
- Ulipristal: a progesterone receptor modulator that works later in the cycle. Within 120 hours
- Copper intrauterine device: the most effective, up to 5 days after the earliest estimated ovulation, and it also provides ongoing contraception
The combined pill also confers non-contraceptive benefits worth knowing: reduced risk of ovarian and endometrial cancer, lighter periods and improved acne, balanced against an increased risk of venous thromboembolism.