View full lesson: http://ed.ted.com/lessons/how-do-contraceptives-work-nwhunter

Contraceptives are designed to prevent pregnancy in three basic ways: they either block sperm, disable sperm before they reach the uterus, or suppress ovulation. But is one strategy better than the other? And how does each one work? NWHunter describes the mechanics behind different kinds of contraceptives.

Lesson by NWHunter, animation by Draško Ivezić.