What Is It?
The birth control pill is a daily pill that contains the hormones estrogen and progesterone that prevent pregnancy (also called the Pill).

How Does It Work?
Most birth control pills contain the combination of the hormones estrogen and progesterone to prevent ovulation (the release of an egg during the monthly cycle). If a woman doesn't ovulate she cannot get pregnant because there is no egg to be fertilized.

One type of birth control pill, known as the Minipill, contains only the hormone progesterone. Although progesterone alone may prevent ovulation, this may not occur reliably every month. The Minipill also works by thickening the mucous around the cervix, which prevents the sperm from entering the uterus. It also affects the lining of the uterus so if the egg is fertilized it cannot attach to the wall of the uterus.

The combination pill comes in either a 21-day pack or a 28-day pack. One hormone pill is taken each day at about the same time for 21 days. Depending on your pack, you will stop taking pills for 7 days or you will take a reminder pill (that contains no hormones) for 7 days. A woman has her period when she stops taking the pills with hormones. Some women prefer the 28-day pack because it helps them stay in the habit of taking a pill every day.

The Minipill is taken every day - there are no reminder pills. On the Minipill you may have no period or you may go several months without a period, which means you are not ovulating. If you are having regular periods, you are probably still ovulating and are at greater risk of getting pregnant.

The Pill works best when it is taken every single day at the same time of day, regardless of whether you are going to have sex. This is especially important with progesterone-only pills. You should not take a friend's or sister's pills. If pills are skipped or forgotten, you are not protected against pregnancy and backup birth control, such as condoms, must be used.

How Well Does It Work?
Over the course of one year about five out of 100 typical couples who rely on the Pill to prevent pregnancy will have an accidental pregnancy. Of course, this is an average figure and the chance of getting pregnant depends on whether you take your birth control pills every day. The Pill is an effective form of birth control, but even missing 1 day increases the chance of getting pregnant.

In general, how well each type of birth control method works depends on a lot of things. These include whether a person has any health conditions or is taking any medications that might interfere with its use. It also depends on whether the method chosen is convenient - and whether the person remembers to use it correctly all the time.

Protection Against STDs?
The birth control pill does not protect against sexually transmitted diseases (STDs). For those having sex, condoms must always be used along with birth control pills to protect against STDs.

Possible Side Effects
The birth control pill is a safe and effective method of birth control. Most young women who take the Pill have no side effects. The side effects that some women have while on the Pill include:

• irregular menstrual bleeding
• nausea, weight gain, headaches, dizziness, and breast tenderness
• mood changes
• blood clots (rare in women under 35 who do not smoke)

Some of these side effects improve over the first 3 months on the Pill. Sometimes a doctor will prescribe a different brand of pill, which may work better with your body and have fewer side effects.

The Pill also has some side effects that most young women are happy about. It usually makes periods much lighter, reduces cramps, and is often prescribed for women who have menstrual problems. Taking the Pill often improves acne, and some doctors prescribe it for this purpose. Birth control pills have also been found to protect against some forms of breast disease, anemia, ovarian cysts, and uterine cancer.

Who Uses It?
Young women who can remember to take a pill each day and who want excellent protection from pregnancy use birth control pills.

Not all women can - or should - use the birth control pill. In some cases, medical or other conditions make the use of the Pill less effective or more risky. For example, it is not recommended for women who have had blood clots, high blood pressure, certain types of cancers, certain types of migraine headaches, or uncontrolled diabetes. It's recommended that girls who have had unexplained vaginal bleeding (bleeding that is not during their periods) or who suspect they may be pregnant should talk to their doctor.

Girls who are interested in learning more about different types of birth control, including the Pill, should talk to their doctor or other health professional.

How Do You Get It?
A doctor or a nurse practitioner must prescribe the pill. A doctor or nurse will do a complete physical exam, along with a pelvic exam. The doctor or nurse will often prescribe 3 months' worth of pills and explain when to begin taking the pill and what to do if pills are missed. When you come back in 3 months, the doctor or nurse will check your blood pressure and ask if you are having any problems. If there are no problems and you want to continue to use birth control pills you'll get another prescription for 6 to 12 months. After that, you should have routine pelvic exams once a year or as recommended by your doctor.

How Much Does It Cost?
The Pill usually costs between $20 and $30 a month, although many health and family planning clinics (such as Planned Parenthood) sell them for even less. In addition, birth control pills and doctor's visits are covered by many health insurance plans.

Remember, abstinence (the decision to not have sex) is the only method that always prevents pregnancy and sexually transmitted diseases (STDs).

Updated and reviewed by: George A. Macones, MD
Date reviewed: April 2003
Originally reviewed by: Neil Izenberg, MD

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