For pregnancy to happen, the following events are essentially needed:

1. Production of sperm and ovum (egg cell)
2. Release of a mature egg from the ovary (ovulation)
3. Fusion of male sperm and female ovum (fertilization)
4. Implantation of a fertilized ovum to inner lining of uterus

When you take i-pill Daily contraceptive pills on a regular basis, ovulation or the release of egg is suppressed. In the absence of an egg, conception is avoided.