What are birth control pills?

Birth control pills (oral contraceptives) are a method of birth control that uses hormones to prevent pregnancy. The man-made female hormones in the pills change a woman's natural hormone levels and prevent her ovaries from releasing an egg each month. The cervix also produces less mucus so that sperm cannot easily enter the uterus. In addition, the lining of the uterus becomes thinner, so it would be more difficult for a fertilized egg to stay in the uterus.

The most commonly used pills are 'combined' pills. They contain man-made forms of two hormones: estrogen and progesterone. There is also a progesterone-only pill (the mini-pill), but it is not as effective.

How are the pills used?

The combined pills usually come in a package of 28 pills. They are also available in 21-pill packs. You and your doctor will decide which type of package is best for you. Your doctor will probably advise you to start taking the pills on the Sunday after your period has started or on the first day of your next period, depending on your preference.

If you are using the 21-pill pack, take one pill every day for 3 weeks. Stop taking the pills for 7 days and then start a new pack.

If you are using the 28-day package, take one pill every day for 4 weeks and then start a new package the next day. The last seven pills contain no medication for birth control; they just keep you in the habit of taking a pill every day. It is important to try to take the pills at approximately the same time every day.

Your period will usually occur soon after the last hormone-containing pill is taken.

Some antibiotics can affect the way birth control pills work in your body. If you are taking antibiotics, tell your doctor. You may need to use an additional form of birth control while you are taking antibiotics.

What if I forget to take a pill?

If you forget to take some of the pills, you will have menstrual bleeding at unpredictable times and you may get pregnant.

If you forget to take one pill, take it as soon as you remember and take your next pill at the usual time. If you miss two consecutive pills, take two pills each day for 2 days and then go back to your regular schedule.

If you miss three or more pills, stop taking the pills and use a different birth control method until your next menstrual cycle starts. If your menstrual cycle doesn't start on schedule, check with your health care provider.

If you have forgotten to take two or more pills and you have missed a period, you might be pregnant. You should stop taking the pills and use other forms of birth control until you are sure you are not pregnant.

Do not stop taking the pills if you have taken them correctly.

When can I start taking oral contraceptives after having a baby?

If you are breast-feeding your baby, you should not take oral contraceptives until you have a good breast-feeding pattern. This will take about 4 to 6 weeks after the birth. Then, a low-dose pill or progesterone-only pill may possibly be used. Talk to your doctor about when you can start the pills again. Also, remember that breast-feeding is not sure protection against pregnancy, so use another form of birth control before you start taking birth control pills again.

If you are not breast-feeding your baby, you generally can begin taking birth control pills 1 to 2 weeks after the birth or when you begin menstruating again. Use condoms and spermicides until you start the pills.

What are the benefits?

The main benefit of birth control pills is that they are effective in preventing pregnancy but do not interrupt lovemaking. Three of every 100 women taking birth control pills becomes pregnant at the end of 1 year.

The pills also may decrease the risk of uterine and ovarian cancer, ovarian cysts, rheumatoid arthritis, and ectopic (tubal) pregnancy. Also, when you use birth control pills, your periods are regular, lighter, and less painful.

Generally, women who have no gynecologic problems before they start taking oral contraceptives have no trouble becoming pregnant after they stop taking birth control pills, regardless of how long they have been taking them. There is no advantage to 'taking a break' from birth control pills unless you have problems specifically related to the pills. When you want to get pregnant, it is recommended that you wait until you have had at least two normal menstrual periods after stopping the pills.

What are the disadvantages?

One disadvantage of birth control pills is that you must remember to take a pill every day.

Problems you may have while you are taking birth control pills include:

• irregular bleeding for the first few months after you start birth control pills

• nausea and vomiting

• weight gain

• breast swelling

• increased appetite

• depression

• headaches

• scant or missed periods

• high blood pressure

• dizziness.

Women who take birth control pills and smoke, especially those over 35 years old, have an increased risk of severe problems such as heart disease and blood clots. The heart disease could cause a heart attack. The blood clots may cause leg pain or swelling, or chest pain.

Have your blood pressure checked after you have taken the pills for 3 months. You should not smoke if you take birth control pills.

Birth control pills do not protect you from sexually transmitted diseases, such as AIDS. Latex condoms are the only safe way to protect against AIDS.

When should I call the doctor?

Call the doctor if you have:

• leg pain or swelling

• loss of vision or double vision

• bleeding irregularities

• more headaches than usual.