Dear elevenstar,

A pregnancy test can detect pregnancy after a missed period — some can even detect it a few days before a missed period. Despite what some people think, pregnancy doesn't start the day a couple has intercourse. It can take up to six days after sex for the sperm and egg to join and form a fertilized egg. Then, it can take up to six days, or more, for the fertilized egg 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.

If a woman is worried that she might be pregnant, she can take a home pregnancy test or go to a health clinic for confidential testing. Women who use home pregnancy tests need to be sure to follow exactly the directions on the package.

A woman who is concerned about unintended pregnancy may want to consider emergency contraception (EC). EC can reduce the risk of pregnancy after unprotected intercourse. Emergency contraception can reduce the risk of pregnancy if started within 120 hours of unprotected vaginal intercourse. The sooner EC is taken, the better. If started within 72 hours of unprotected sex, it can reduce the risk of pregnancy by 75 to 89 percent.

If a woman has had unprotected sex within the last 120 hours (five days), and needs an appointment to receive EC, she can call 1-800-230-PLAN for a Planned Parenthood center nearest her.

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.