McKesson Clinical Reference Systems: Women's Health Advisor 2002.2
Spanish version

What is contraception?

Contraception (birth control) is the term used for the prevention of pregnancy. There are many ways to try to prevent pregnancy when you are having sexual intercourse. Some are much more effective than others. They include the use of hormone medications, contraceptive devices (barriers), periods of avoiding sex, and surgery. What follows is basic information on these various methods. This will help you decide which method is right for you and your lifestyle.

Remember that you need to consider whether the method you choose will also protect you from getting sexually transmitted diseases. Sometimes you may need to use more than one method to prevent pregnancy AND disease. The latex male condom and the polyurethane female condom are the best protection currently available against sexually transmitted diseases. They are the only ways to reduce your risk of being infected during sex with HIV, the virus that causes AIDS. The birth control methods using hormones, natural family planning, and withdrawal do not give any protection against disease.

What are the different methods of contraception?

Hormone Medications

Birth control pills (oral contraceptives), the Norplant implant, the shots Depo-Provera and Lunelle, the vaginal contraceptive ring (NuvaRing), and a transdermal patch (Ortho Evra) contain manufactured forms of the hormones estrogen and/or progesterone. The hormones stop a woman's ovaries from releasing an egg each month. They also cause the cervical mucus to thicken, which then acts as a barrier to sperm.

• A woman takes birth control pills according to a daily schedule prescribed by her health care provider.
• Depo-Provera, which contains a strong progesterone hormone, is given as a shot. It prevents pregnancy for 3 months.
• Lunelle contains estrogen and progesterone and is given as a shot. It prevents pregnancy for 1 month.
• Norplant is a set of small, thin, flexible capsules containing progesterone that are placed under the skin of a woman's arm. Norplant prevents pregnancy for up to 5 years, the length of time recommended for leaving the implants in place.
• NuvaRing is a flexible ring that is inserted into the vagina for 3 weeks, removed for 1 week, and then replaced with a new ring. Estrogen and progesterone are released into your body from the ring.
• Ortho Evra is a patch that is put on the skin. The hormones are on the adhesive side of the patch. Each patch is worn for 1 week then thrown away. This is repeated 2 more times with 2 more patches and then no patch is worn for 1 week.

All of these hormonal forms of birth control require visiting your health care provider for a prescription, shot, or placement of the capsules.

Contraceptive Devices

Most contraceptive devices form physical or chemical barriers that stop sperm from entering a woman's uterus.

The male condom is a tube of thin material (latex rubber is best) that is rolled over the erect penis just before any contact of the penis with a woman's genitals. The male condom provides the best protection against sexually transmitted diseases, including HIV and hepatitis B.

The female condom is a 7-inch-long pouch of polyurethane with two flexible rings. It is inserted into the vagina before intercourse. It covers the cervix, vagina, and area around the vagina. Like the latex male condom, the female condom provides protection against some sexually transmitted diseases, including HIV and hepatitis B.

Spermicides are sperm-killing chemicals that are available as foam, jelly, foaming tablets, vaginal suppositories, or cream. They are inserted into the vagina no earlier than 30 minutes before intercourse. Spermicides should NOT be used alone. They should be used with another contraceptive, such as a condom, for increased effectiveness. Spermicides containing nonoxynol-9 provide some protection against viruses. However, in general, spermicides do not protect against sexually transmitted diseases.

Condoms and spermicides can be purchased at drug and grocery stores without a prescription.

The diaphragm is a soft rubber dome stretched over a flexible ring. No more than 3 hours before intercourse, the diaphragm is filled with a spermicidal jelly or cream and inserted into the vagina and over the cervix. (The cervix is the opening of the uterus).

The cervical cap is made of latex rubber or plastic and is shaped like a cup. It is smaller and more rigid than a diaphragm. No more than 24 hours before intercourse, the cap is filled with a spermicidal jelly or cream and inserted into the vagina and over the cervix.

The intrauterine device (IUD) is a small plastic device containing copper or hormones. Instead of stopping sperm from entering the uterus, the IUD changes the physical environment of the reproductive tract, which prevents the egg from being fertilized or implanting and growing in the uterus. An IUD is inserted into the uterus by a medical professional. Depending on the type, it may be worn from 1 to 10 years before it must be replaced.

The diaphragm and cervical cap require a fitting by your health care provider. If you choose to use an IUD, you will need to see your provider for insertion and removal of the IUD.

Natural Family Planning (Periodic Abstinence) and the Withdrawal Method

The natural family planning methods of birth control do not depend on any devices or drugs. To prevent pregnancy you cannot have sex for about 7 to 10 days during each menstrual cycle. To know when it is safest to have sex, a woman must record her body temperature and changes in cervical mucus every day. For most people, other methods of birth control are more reliable.

The withdrawal method involves removing the penis from the vagina just before semen starts coming out (ejaculation). Often sperm are deposited in the vagina before or during withdrawal, making this method unreliable.

Sterilization

Sterilization is the surgical closing of the tubes that normally carry the sperm or eggs. A woman or man who undergoes sterilization will no longer be able to conceive children.

In a vasectomy a surgeon cuts and seals off the tubes that carry sperm in a man. When a woman is sterilized, her fallopian tubes, which carry the eggs from the ovaries to the uterus, are sealed off. A vasectomy is a more minor surgical procedure than female sterilization.

These surgical procedures can be reversed but pregnancy may not result. In women, the risk of ectopic (tubal) pregnancy is increased.

How well do the various methods prevent pregnancy?

The following chart shows the typical failure rates of birth control methods discussed in this handout. The failure rate is the number of pregnancies expected per 100 women during 1 year of using the method. The rates vary, depending on how correctly and consistently each method is followed. If a method is used perfectly, the failure rate is lower than the typical rate shown here. Use of more than one method (for example, birth control pills and condoms) can decrease the chances of failure.

 
                         Percentage of Women Experiencing 
                         an Accidental Pregnancy with the 
 Birth Control                   First Year of Use 
    Method                        (typical use) 
-------------------------------------------------------------
Spermicides                          26% 
Natural Family Planning
  (Periodic Abstinence)              25% 
Withdrawal                           19% 
Cervical Cap with Spermicide
  Women who have given birth         40% 
  Women who have not given birth     20% 
Diaphragm with Spermicide            20% 
Condom 
  Female                             21% 
  Male (latex condom)                14% 
Pill                                  5% 
IUD 
  Progesterone T                      2.0% 
  Copper T 380A                       0.8% 
Injection (Depo-Provera)           less than 1%
Injection (Lunelle)                less than 1%*
Implant (Norplant--6 capsules)     less than 1%  
Patch (Ortho Evra)                    1% 
Vaginal ring (NuvaRing)               1 to 2% 
Female Sterilization               less than 1%  
Male Sterilization                 less than 1%  
No Method                            85% 
-------------------------------------------------------------
* This is the failure rate for Lunelle if the shots are 
  received on time. 

Note: These failure rates are based on Hatcher, Robert A.,  
Contraceptive Technology (17th edition; Irvington Pub., 
1998) and manufacturer's information if the data for more 
recently developed methods is not included in Hatcher.  
"Typical use" refers to a method's reliability in real life, 
when people don't always use a method properly. 
-------------------------------------------------------------

As you can see, other than sterilization, the hormone medications and the IUD are the most effective methods of birth control. However, the diaphragm and cervical cap can be nearly as reliable if they are used properly. The least reliable methods are spermicide alone, natural family planning, withdrawal method, and female condom.

This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.