Introduction
Hormonal methods work by mimicking the natural hormones of the woman's body: estrogen and progesterone or just progesterone. They prevent pregnancy as follows:
- ovulation does not occur (without an egg, sperm cannot fertilize)
- the lining of the uterus thins (in case a woman did ovulate (i.e., missed her pills towards the end of the pack), implantation would be difficult
- the cervical mucous thickens (making it difficult for sperm to enter the uterus)
Efficacy of Hormonal Methods
| Hormonal Method | Use Effectiveness (Actual Use) | Theoretical Effectiveness (Perfect Use) |
|---|---|---|
| Combined Oral | 92% | 99.7% |
| Patch | 92% | 99.7% |
| NuvaRing | 92% | 99.7% |
| Depo Provera | 97% | 99.95% |
| Progestin-only Mini Pill | 92% | 99.7% |
Reviewed by Danielle Chard, RN, BSc Nursing 20/20/07
