Body basics
How birth control works
Editorially reviewed on October 29, 2026. [TODO: medical reviewer]
Quick answer
Combined pills, the implant and the injectable mainly stop ovulation, so no egg is released. Progestins also thicken cervical mucus so sperm cannot get through. Copper IUDs stop sperm and egg meeting. None of them cause an abortion.
Ovulation
An egg is released. Combined pills, the implant and the injectable mainly work by preventing this.
How it works
Mechanisms are summarised from the WHO Family Planning Handbook.[src] Emergency contraceptive pills work mainly by delaying ovulation.[src] Next: how effective each method is.
This guide is for information. Talk to a doctor before starting, stopping or switching birth control.
Sources
- Family Planning: A Global Handbook for Providers, WHO and Johns Hopkins CCP
- Emergency contraception (fact sheet), World Health Organization