Birth Control Pill
Effectiveness in Preventing Pregnancy
- Of 100 women who use this method each year, about five to nine of them may become pregnant.
- The risk of pregnancy is lower in women who take birth control pills correctly—every day at about the same time.
What is the birth control pill?
The birth control pill, also known as oral contraceptive or “the pill,” is a medication taken daily to prevent pregnancy. Some women take the pill for reasons other than preventing pregnancy. There are two main kinds of birth control pills:
Combined pills: Contain two hormones, estrogen and progestin. Hormones are chemicals that control how different parts of your body work. These pills are taken every day and prevent pregnancy by keeping the ovaries from releasing eggs. The pills also cause cervical mucus to thicken and the lining of the uterus to thin. This keeps sperm from meeting with and fertilizing an egg.
Progestin-only pills (or “mini-pills”): Contain only one hormone, progestin, which causes cervical mucus to thicken and the lining of the uterus to thin. This keeps sperm from reaching the egg. Less often, mini-pills prevent pregnancy by keeping the ovaries from releasing eggs.
How do I use it?
Combined pills are typically packaged as 21 “active” pills that contain hormones. One pill is taken daily for three weeks, followed by one week of not taking pills. Others are packaged as 28 pills that include 21 “active” pills taken daily, followed by one week of “inactive” reminder pills that do not contain hormones.
Some newer formulations have increased the number of active pills to 24 and reduced the inactive pills to four. With all combined pill formulations, protection against pregnancy continues during the week that no active pills are taken.
Mini-pills come only in packages of 28-day “active” pills. Like combined pills, it is important to take mini-pills every day and to take them at the same time each day. If you are late taking a mini-pill by more than three hours, you will need to not have sex or use an additional type of birth control (such as a condom or sponge) for two consecutive days to prevent pregnancy, but continue also to take the mini-pill every day.
All types of birth control pills should be taken exactly as directed by your healthcare provider, even on days when you do not have sex.
How effective is it?
Of 100 women who use this method each year, about nine women may become pregnant on the combined pills, and five may become pregnant on the mini-pills. The risk of pregnancy is much less for women who take the pill correctly—every day at about the same time. Certain medications such as Rifampin (an antibiotic taken to treat tuberculosis), some anti-seizure medications, and supplements (such as St. John’s Wort) may make the pill less effective. Talk with your healthcare provider if you have any questions about birth control pills and other medications or supplements.
How do I get it?
You may need a prescription from your healthcare provider, depending on the state where you are getting birth control pills. Once you have a prescription, birth control pills can be purchased at pharmacies or obtained from a health center, including a family planning center.
Advantages of the birth control pill
- The pill is easy to use.
- Birth control pills are safe and work well in preventing pregnancy.
- Using the pill means you do not have to think about birth control when you want to have sex.
- Combination pills may offer other benefits such as fewer menstrual cramps, decreased menstrual blood loss, and less acne. These pills also may reduce the risk of some cancers that affect reproductive organs.
- Fertility returns to normal when you discontinue use of the pill.
Drawbacks of the birth control pill
- The pill does not protect against sexually transmitted diseases (STDs), including HIV. Always use a condom to reduce the risk of STDs.
- You must take your pills every day, and some pills must be taken in a certain time frame each day.
- Certain medications such as Rifampin (an antibiotic taken to treat tuberculosis), some anti-seizure medications, and supplements (such as St. John’s Wort) may make the pill less effective.
- Combined pills may cause nausea, changes in your menstrual cycle, breast tenderness, or headaches. Discuss your medical history with your healthcare provider before using any birth control pill and let them know if you develop any side effects.
- It is uncommon, but some women develop high blood pressure when taking the pill.
- It is uncommon, but the use of the combined pill increases the risk of blood clots, heart attack, and stroke in some women.
Did You Know?
Condoms add extra protection against pregnancies and STDs when used with other birth control methods.
Content last reviewed on June 8, 2017