Birth control pills are made of fake, or synthetic, hormones that stop a female from releasing an egg, which is called ovulating. With no egg there can be no pregnancy. A birth control pill must be taken every day, preferably around the same time, to work. If you miss a pill, or take them at different times on different days, they may not work. 

After one full week of taking the Pill, it becomes effective at preventing pregnancy. When used perfectly -- taken every day at around the same time -- it prevents pregnancy 99 percent of the time. Factor in human error -- missing a day or taking them at different times -- that rate drops to 95 percent.

Birth control pills can come with side effects, both good and bad. They include slight weight gain, lighter periods, less acne, a bigger appetite, mood swings, bleeding between periods, and changes in sex drive. For most girls, annoying side effects are gone within three months of beginning the pill.  The pill offers NO protection against sexually transmitted infections, so you need to also use a condom whenever you have sex.

You need a prescription to get the Pill. The cost varies, depending on where you go to get a prescription. Typically, you�ll pay less if you go to a family planning clinic, like Planned Parenthood ($10-$20 per month), versus a private doctor�s office. But, it really depends on whether you have health insurance that you can use. When you call to make the appointment, be sure to ask.