Birth Control Pills - Your Guide

Birth control is a way for men and women to prevent pregnancy. There are many different methods of birth control, including hormonal contraception (HC) such as "the Pill."

The Pill is taken by mouth by the woman to prevent pregnancy, and when taken correctly, is up to 99.9% effective. However, the Pill does not protect against sexually transmitted diseases, including HIV (the virus that causes AIDS). The latex male condom provides the best protection from most STDs. Other types of combined estrogen and progestin hormonal contraception include the patch and the vaginal ring.

How Does Hormonal Contraception Work?

Normally a woman becomes pregnant when an egg released from her ovary (the organ that holds her eggs) is fertilized by a man's sperm. The fertilized egg attaches to the woman's womb (uterus), where it receives nourishment and develops into a baby. Hormones in the woman's body control the release of the egg from the ovary and prepare the body to accept the fertilized egg.

HC (the pill, the patch, and the vaginal ring) all contain a small amount of synthetic estrogen and progestin hormones. These hormones work to inhibit the body's natural cyclical hormones to prevent pregnancy. Pregnancy is prevented by a combination of factors. The HC usually stops the body from releasing an egg from the ovary. HC also changes the cervical mucus to make it difficult for the sperm to find an egg. HC can also prevent pregnancy by making the lining of the womb inhospitable for implantation.

A new option for the HC is extended-cycle pill use; the first one approved is called Seasonale. Seasonale contains the same hormones as in other birth control pills, but they are taken in a longer cycle to reduce the number of yearly menstrual periods from 13 periods a year to only four periods a year. Therefore, women menstruate only once each season.

Seasonale contains the same combination of two hormones commonly used in other hormonal contraceptives, and are in low doses taken continuously for 12 weeks followed by 1 week of inactive pills which causes a menstrual cycle.

What Are Mini Pills?

These are pills that contain only one hormone (progestin). They do not contain estrogen and may be prescribed in women who are breastfeeding or in women who experience nausea with estrogen.

How Do Mini Pills Work?

Mini pills work by thickening the cervical mucus so the sperm cannot reach the egg. The hormone in the pills also changes the lining of the uterus, so that implantation of a fertilized egg is much less likely to occur. In some cases, mini pills stop ovulation (the release of an egg). A pill is taken every day.

How Effective Are Mini Pills?

If mini pills are used consistently and correctly, they are about 95% effective-somewhat less effective than standard HC.