Progestin-Only Birth Control Pills

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Progestin-Only Birth Control Pills

What is a progestin-only birth control pill?

A progestin-only birth control pill is often called the "mini-pill." Regular birth control pills have 2 female hormones: estrogen and progestin (a synthetic version of the naturally-occurring hormone progesterone). The mini-pill has only progestin in it. Because this pill doesn't contain estrogen, it may not have as many side effects.

How does the progestin-only pill work?

This pill works in three different ways. First, the progestin-only pill thickens the mucus between your uterus and your vagina. Sperm have a hard time getting through the thick mucus to reach the egg. Second, like regular birth control pills, the progestin-only pill makes your body "think" that you are pregnant and stops your ovary from releasing an egg. This does not happen as often as with combination birth control pills. Forty percent of women taking the progestin only pill will continue to ovulate.

Third, the mini-pill causes changes in your uterus (where a baby grows) that make your uterus less likely to let a pregnancy get started, even if an egg is released.

Is the progestin-only pill better than regular birth control pills?

The progestin-only pill is better than regular birth control pills if you are breastfeeding because the mini-pill will not change your milk production (estrogen may reduce the amount of breast milk).

The mini-pill may be safer for some women to use than regular birth control pills. This pill is safer for women who are older than 35 and smoke, have high blood pressure, or have a history of blood clots.

Regular birth control pills make some women feel sick to their stomach or have severe headaches due to the estrogen in them. The progestin-only pill might not cause this problem.

If I use the progestin-only pill, can I still get pregnant?

There is no contraceptive method that is perfect, even when used correctly. Two or 3 out of every 100 women who use the progestin-only pill correctly, could still get pregnant. The risk of pregnancy is almost the same as the risk with regular birth control pills. With progestin-only pills, it's very important that you take your pills at exactly the same time every day. If you don't take the pills at the same time every day, your risk of pregnancy increases. Remember that both kinds of birth control pills are better at preventing pregnancy than condoms alone.

Does the progestin-only pill have any disadvantages?

You might have bleeding between your periods for several months after you start taking the progestin-only pill. This can be inconvenient, but it is not a health risk. The bleeding may go away on its own after you use the mini-pill for a few months. If the bleeding seems heavy or if it bothers you, talk to your doctor about it.

Like regular birth control pills, the progestin-only pill has to be taken for a week before it can protect you from pregnancy. So for the first week, you need to use another kind of contraception, such as condoms, along with the mini-pill.

The mini-pill works best if you take it every day at the same time of day. Timing is much more important for the progestin-only pill than for regular birth control pills. If you are more than three hours late taking the progestin-only pill, you should take your missed dose right away and use a backup method of contraception (such as a condom) for the next 2 days.

If you miss a day completely, you have to use a second method of birth control for one week. You can't take two mini-pills the next day to make up for a missed pill.

Like all birth control pills, the progestin-only pill does not protect you from getting a sexually transmitted infection.


  • Using Progestins in Clinical Practice by BS Apgar, M.D., M.S. and G Greenberg, M.D., M.A.( 10/15/00,