Dear skimergirl,

Good question! The pill contains hormones similar to the estrogen and progesterone made by a woman's ovaries. These hormones work to prevent the ovaries from releasing an egg (ovulation). They can also thicken cervical mucus to prevent sperm from joining with an egg. The ring and the patch work in the same ways. Combined hormone pills are more likely to prevent ovulation. Progestin-only pills are more likely to thicken cervical mucus.

If you start taking the pill within five days of the start of your period, pill protection begins immediately. If you start taking it at any other time, pill protection begins one week later. Used correctly and consistently, the pill is up to 99.7 percent effective against pregnancy. Just remember — only female and latex condoms also reduce the risk of sexually transmitted infections.

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.