Dear caezeriv,

Good question! Here's how it works: Fertilization happens in one of the fallopian tubes, which carries an egg from an ovary to the uterus. It can take up to six days after intercourse for sperm and egg to join and form a fertilized egg. Usually, it's because the sperm gets into the fallopian tube before the egg is released. Once there, the sperm wait for an egg to arrive. After fertilization, it can take up to six days for the fertilized egg to begin to attach itself to the lining of the uterus. Pregnancy begins when this happens.

Pregnancy tests work by detecting a hormone called the human chorionic gonadotropin hormone (HCG). HCG doesn't start being released until the fertilized egg implants itself and pregnancy begins.

Hope this information helps!

Take care,

teenwire.com^® Editors

This column is for informational purposes only and is not intended to constitute medical advice, diagnosis, or treatment. If you have a medical problem, please call toll-free 1-800-230-PLAN for an appointment with the Planned Parenthood health center nearest you.