Contraception

INTRODUCTION — Contraception or birth control is the use of a medication, device, or method to prevent pregnancy. Such devices or techniques, known as contraceptives, work to: Prevent ovulation, the release of eggs from a woman's ovary Prevent sperm from getting into the uterus and fallopian tubes (where fertilization of the egg normally occurs) Prevent implantation of the embryo (fertilized egg) into the uterine lining (endometrium)

Most women of reproductive age in the United States use some form of contraception. However, unintended pregnancy is still a common problem in this country. Almost one-half of pregnancies are estimated to be unintended.

This topic is an overview of all methods of birth control. More detailed discussions of hormonal, long-term, and barrier birth control methods are available separately. (See "Patient information: Long-term methods of birth control" and see "Patient information: Barrier methods of birth control" and see "Patient information: Hormonal methods of birth control").

EFFECTIVENESS OF CONTRACEPTION — Most contraceptive methods are quite effective if used properly. However, the actual effectiveness of a method can differ from "perfect use" effectiveness (show table 1A-1B). Contraceptives fail for a number of reasons, including improper use, failure to follow treatment recommendations, or failure of the medication, device, or method itself.

Certain contraceptives, such as intrauterine devices (IUDs) and injectable contraceptives, have a low risk of failure (pregnancy). This is because compliance (using the method correctly or taking the medication on a regular basis) is not a major factor. (See "Patient information: Long-term methods of birth control").

Oral contraceptives (birth control pills) have a low pregnancy rate if they are taken properly (ie, pills are taken every day). However, the actual pregnancy rate is much higher because many women forget to take the pill every day. (See "Patient information: Hormonal methods of birth control").

Other contraceptive methods such as the condom, diaphragm/cervical cap, and spermicides can be very effective if used properly. However, these methods are also associated with higher "actual" pregnancy rates because of incorrect or inconsistent use. (See "Patient information: Barrier methods of birth control").

Overall, contraceptive methods that are designed for use at or near the occurrence of intercourse (eg, the condom, diaphragm) are generally less effective than contraceptive methods that are unrelated to the occurrence of sexual activity (eg, intrauterine device, oral contraceptives).

Women who are at risk of pregnancy and are using birth control should also have a supply of emergency contraceptive pills on hand (See "Emergency contraception" below).

CHOOSING A METHOD — It can be difficult to decide which birth control method is best due to the variety of options available. The best method is one that will be used consistently, is acceptable to the woman and her partner, and does not cause bothersome side effects. Other factors to consider include: Efficacy Convenience Duration of action Reversibility and time to return of fertility Effect on uterine bleeding Frequency of side effects and adverse events Affordability Protection against sexually transmitted diseases

No method of contraception is perfect. Each woman must balance the advantages of each method against the disadvantages and then choose the most effective method that she feels she will be able to use consistently and correctly. A list of questions that are useful for defining a person's preferences are provided in the table (show table 2).

EMERGENCY CONTRACEPTION — Emergency contraception (EC, also known as postcoital contraception or the morning-after pill) refers to the use of drugs to prevent pregnancy in women who have had recent unprotected intercourse (including sexual assault), or who have had a failure of another method of contraception (eg, broken condom). As many as 30 percent of women will become pregnant after a single unprotected act of sex that occurs near the time of ovulation. Use of EC significantly reduces the chance of pregnancy, but pregnancy may still occur.

Experts are uncertain about how EC prevents pregnancy. Since these drugs are taken within hours of intercourse and implantation does not occur until approximately five to seven days after ovulation, use of EC does not interrupt pregnancy (the United States Federal policy is that a woman is considered pregnant once a conceptus has implanted; however, some consider pregnancy to begin at conception).

Several options are available for EC (show table 3 and show table 4). Plan B is a pill pack that contains two 0.75 mg tablets of levonorgestrel, both of which should be taken as soon as possible after unprotected sex. It is also acceptable to take one pill as soon as possible, followed by the second pill 12 hours later (this is the instruction given by the manufacturer). The cost is approximately $40. The Plan B regimen is more effective and better tolerated than regimens using oral contraceptive pills that contain estrogen (eg, Ovral two tablets twelve hours apart or Lo/Ovral four tablets 12 hours apart).

Nausea and vomiting are the major side effects of the estrogen-containing regimen. A medication to reduce nausea and vomiting can be taken one hour before the first dose. Nausea and vomiting is less common with the levonorgestrel method. However, if levonorgestrel is vomited within one hour of taking it, a medication to prevent nausea can be taken, followed by a repeat of the EC dose.

EC is most effective when taken as soon as possible after intercourse. However, studies have shown that it is somewhat effective for up to 120 hours (five days) after intercourse, and may be started up to that time if necessary. After five days, insertion of a copper intrauterine device (IUD) is considered the best way to prevent pregnancy. (See "Patient information: Long-term methods of birth control").

A risk of pregnancy still exists if the woman has unprotected intercourse after EC pills have been taken. Therefore, another method of contraception (eg, condoms) should be used for the rest of the cycle. A second dose of EC may be used if a second episode of unprotected intercourse occurs anytime after the first dose.

A woman who is sexually active and does not want to become pregnant can consider purchasing EC before it is needed. This would eliminate any delay in taking the first dose. In the United States, EC is approved as an over the counter medication for individuals (men or women) age 18 and older; proof of age (a government issued ID) is required. Younger patients still require a prescription. Plan B is only available at sites with a licensed pharmacist.

ORAL CONTRACEPTIVES — Most oral contraceptives, also referred to as "the pill," contain a combination of female hormones, estrogen and progestin (a progesterone-like medication). A list of available pills is shown in the table (show table 5). A full discussion of hormonal birth control methods is available separately. (See "Patient information: Hormonal methods of birth control").

The combination pill reduces the risk of pregnancy by: Preventing ovulation Keeping the mucus in the cervix thick and impenetrable to sperm Keeping the lining of the uterus thin

Other non-contraceptive benefits of the pill include a reduction in: Menstrual cramps or pain (dysmenorrhea) Ovarian cancer Cancer of the endometrium (uterine lining) Acne Iron-deficiency anemia (a low blood count due to low iron levels)

Efficacy — When taken properly, OCs are a very effective form of contraception. Although the failure rate is less than one percent when pills are taken perfectly (same time every day, no missed pills), the actual failure rate is 8 percent due primarily to missed pills or failure to restart the pill after the seven-day pill-free interval (show table 1A-1B).

Missed pills are a common cause of contraceptive failure. In general, an active pill should be taken as soon as possible after a pill has been missed. Back-up contraception should be used for seven days if more than two pills are missed.

Side effects — Side effects of the pill include: Nausea, breast tenderness, bloating, and mood changes, which typically improve after two to three months. Breakthrough bleeding or spotting. This is particularly common during the first few months of taking oral contraceptives. Forgetting a pill can also cause breakthrough bleeding.

Women taking the pill should notify their healthcare provider if they experience abdominal pain, chest pain, severe headaches, eye problems, or severe leg pain, as these could be symptoms of several serious conditions including heart attack, blood clot, stroke, liver, and gallbladder disease.

Progestin only pills — Some pills contain only progestin (called the mini-pill), which is useful for women who cannot or should not take estrogen. This includes women who are breastfeeding or who have aggravation of migraines or high blood pressure with combination contraceptive pills. Progestin only pills (or mini-pills) are as effective as combination pills when taken at the same time every day, but there is a slightly higher failure rate of the mini pill if the woman is more than three hours late in taking it. A backup method of birth control should be used for seven days if a pill is forgotten or taken more that three hours late.

INJECTABLE CONTRACEPTION — The only injectable contraceptive currently available in the United States is medroxyprogesterone acetate or DMPA (Depo-Provera®). DMPA is injected deep into a muscle, such as the buttock or upper arm, once every three months. A preparation that is given subcutaneously (under the skin) is also available. A full discussion of hormonal birth control methods is available separately. (See "Patient information: Hormonal methods of birth control").

DMPA prevents ovulation and alters the cervical mucus, making the cervix impenetrable to sperm. DMPA also thins the uterine lining. Women who receive their first DMPA injection more than seven days after their menstrual period should use a second form of contraception (eg, condoms) for seven days. DMPA is very effective, with a failure (pregnancy) rate of less than one percent (show table 1A-1B).

Side effects — The most common side effects of DMPA are irregular or prolonged bleeding and spotting, particularly during early therapy. Up to 50 percent of women completely stop having menstrual periods (amenorrhea) after one year of DMPA use. Menses generally return within six months of the last DMPA injection.

A full discussion of hormonal birth control methods is available separately. (See "Patient information: Hormonal methods of birth control").

TRANSDERMAL CONTRACEPTION (SKIN PATCHES) — Transdermal contraceptive patches contain estrogen and progestin, similar to oral contraceptives. The patch is as effective as oral contraceptives, and may be preferred by some women because it does not require daily dosing (show table 1A-1B). Ortho Evra is the only transdermal contraceptive available in the United States. Risks and effectiveness are similar to those of oral contraceptive pills. However, the patch appears to deliver a higher overall amount of estrogen than the pill. There is concern that this could increase the risk of blood clots, although this has not been proven.

The patch is worn for one week on the upper arm, shoulder, upper back, or hip. After one week, the old patch is removed and a new patch is applied; this is done for three weeks. During the fourth week, no patch is worn; the menstrual period occurs during this week.

VAGINAL RING — A flexible plastic vaginal ring (Nuvaring®) contains estrogen and a progestin, which is slowly absorbed through the vaginal tissues. This prevents pregnancy, similar to an oral contraceptive. It is worn inside the vagina for three weeks, followed by one week when no ring is used; the menstrual period occurs during this time. The ring is not noticeable, and it is easy for most women to insert and remove. It may be removed for up to three hours if desired, such as during intercourse, although it is not usually felt by the sexual partner. Risks and side effects are similar to those of oral contraceptives.

CONTRACEPTIVE IMPLANT — A single-rod progestin implant, Implanon, is available in the US and elsewhere. It provides three years of protection from pregnancy as progestin is slowly absorbed into the body. It is effective within 24 hours of insertion. Irregular bleeding is the most bothersome side effect. Fertility returns rapidly after removal of the rod.

BARRIER METHODS — This type of contraceptive physically blocks or otherwise prevents sperm from entering the uterus and reaching the egg for fertilization. Barrier contraceptives include the condom, diaphragm, and cervical cap. A full discussion of barrier methods of birth control is available separately. (See "Patient information: Barrier methods of birth control").

Male condom — The male condom is a thin, flexible sheath, or cover, placed over the penis to prevent semen from entering the vagina during sexual intercourse. To help ensure optimal effectiveness and protection, men who use condoms must carefully follow instructions for their use. Condoms are most effective when used with a vaginally-applied spermicide (see "Spermicide" below); use of the male condom and a vaginal spermicide is as effective as a hormonal method of contraception, and is more effective to prevent pregnancy than a condom alone. However, spermicidal condoms (those that are packaged with spermicide applied to the condom) are no more effective and expire faster than condoms without spermicide. Oil-based lubricants (eg, suntan oil, petroleum jelly, whipped cream) should not be used with latex condoms because this can cause breakage of the condom.

Many women who choose a contraceptive other than condoms also choose to use condoms to decrease their risk of acquiring a sexually transmitted disease.

Female condom — The female condom is worn by a woman to prevent semen from entering the vagina. It is a sheath made of polyurethane, and is prelubricated with a silicone-based lubricant. There is a soft, flexible ring at each end. The edges of the ring at the closed end of the sheath are squeezed together and then inserted as far as possible into the vagina; upon release, the ring will open to hold the condom in place. The ring at the open end of the sheath remains outside the vulva, resting against the labia. The woman should check to make sure the condom is not twisted.

Diaphragm/cervical cap — The diaphragm and cervical cap fit over the cervix, preventing sperm from entering the uterus. These devices are available in latex (the Prentif cap) or silicone rubber (FemCap) in multiple sizes, and require fitting by a clinician. These devices must be used with a spermicide and left in place for six to eight hours after sexual intercourse. The diaphragm must be removed after this period. However, the cervical cap can remain in place for up to 24 hours.

Spermicide — Spermicides are chemical substances that destroy sperm. They are available in most pharmacies without a prescription. Spermicides are available in a variety of forms including gel, foam, cream, film, suppository, and tablet.

INTRAUTERINE DEVICES (IUD) — IUDs are inserted by a healthcare provider through the vagina and cervix, into the uterus. Most are made of molded plastic and include an attached string that projects through the cervix into the vagina, enabling a woman to check that the device remains in place.

The currently available IUDs are safe and effective. These devices include: Copper-containing IUDs prevent pregnancy by preventing sperm from reaching the fallopian tubes. Copper-containing IUDs remain effective for at least 10 years. Levonorgestrel-releasing IUDs, prevent pregnancy by thickening the cervical mucus and thinning the endometrium (the lining of the uterus). They also decrease menstrual bleeding by 40 to 90 percent and decrease pain associated with periods. They can be left in place for up to five years, and are highly effective in preventing pregnancy. Some women stop having menstrual periods entirely; this effect is reversed when the IUD is removed.

STERILIZATION — Sterilization is a procedure that permanently prevents a person from becoming pregnant or able to have children. Tubal ligation and vasectomy are the two most common sterilization procedures. Sterilization should be considered permanent, and should only be considered after a careful discussion of all available options with a healthcare provider. (See "Patient information: Surgical sterilization of women" and see "Patient information: Vasectomy").

Tubal ligation — Tubal ligation is a sterilization procedures for women that surgically cuts, blocks, or seals the fallopian tubes to prevent pregnancy. The procedure is usually done in an operating room as a day surgery. Women who have recently delivered a baby can undergo tubal ligation before going home. It may be done at other times as well. A separate topic review is available. (See "Patient information: Surgical sterilization of women").

Essure® — Essure® is a permanent birth control method that requires surgical placement of a tiny coil mechanism into each of the fallopian tubes. The coil blocks the fallopian tubes three months after placement in most women. Placement is done after the woman receives local anesthesia (numbing medicine is injected into the cervix to prevent pain). A back up method of contraception (eg, oral contraceptive or condom) is needed until testing confirms that the fallopian tubes are completed blocked; this is usually performed three months after coil placement.

Vasectomy — Vasectomy is a sterilization procedure for men that surgically cuts or blocks the vas deferens, the tubes that carry sperm from the testes. It is a safe, highly effective surgical procedure that can be performed in a doctor's office under local anesthesia. Following surgery, another contraceptive (eg, condoms) must be used for approximately three months, until a semen analysis confirms that there are no sperm present. A separate topic review is available. (See "Patient information: Vasectomy").

OTHER METHODS — Some women and their partners cannot or choose not to use the contraceptive methods mentioned above due to religious or cultural reasons. Alternate birth control options include periodic abstinence and withdrawal.

Periodic abstinence — Periodic abstinence involves trying to predict the time of the month when a woman is most fertile, and abstaining from sexual intercourse during that time. Different methods may be used to help determine the fertile period:

Rhythm or calendar method — This uses the date of the last menstrual period to determine a woman's most fertile period. The first day of the fertile period is calculated by subtracting 18 days from the shortest menstrual cycle. The menstrual cycle is defined as the number of days from the start of one period to the start of the next period. The last day of the fertile period is calculated by subtracting 11 days from the length of the longest cycle. For example, if a woman's menstrual cycle varies from 28 to 30 days, she should refrain from intercourse from days 10 to 19 of each cycle. Day 1 is the first day of bleeding. This method is not appropriate for a woman who has irregular menstrual cycles and women who have recently delivered a baby or who are breastfeeding.

Basal body temperature — This method is based upon changes in body temperature that occur during a woman's cycle. A woman takes her temperature before getting out of bed in the morning; this is called the basal body temperature. Basal temperature rise slightly (about 0.5º F) after release of the egg. Intercourse should be avoided between the start of the menstrual cycle (day one) until three days after the temperature rises. For most women, this requires abstinence for two weeks. This method is not recommended for women who breastfeeding or nearing menopause.

Cervical mucus — This method uses the color, amount, and consistency of a woman's cervical mucus, which change through a woman's cycle. During ovulation, the mucus is typically watery and in larger amounts than at other times. Intercourse should be avoided when watery cervical mucus first appears until three to four days after the heaviest day of mucus production.

When used perfectly, basal body temperature plus cervical mucus monitoring methods are more effective than the calendar or rhythm method. The estimated failure rates are 3 and 9 percent, respectively (show table 1A-1B). However, failure rates may be as high as 86 percent (with a 28 percent risk of pregnancy per cycle) if used incorrectly.

Withdrawal — Also known as coitus interruptus, the withdrawal method requires the man to withdraw his penis from the vagina before ejaculation. Pregnancy may occur if withdrawal occurs too late or if sperm is released before orgasm (in preejaculatory fluid). With this method, contraceptive failure rates may be as high as 18 to 20 percent (show table 1A-1B).

Breastfeeding — Breastfeeding after childbirth has limited effectiveness in preventing pregnancy due to a delay in the return of ovulation. Approximately 88 percent of women who breastfeed exclusively (meaning that no formula is given and the baby is fed on demand) do not ovulate for six months. If the woman does not have a menstrual period, she is more than 98 percent protected from pregnancy for the first six months (show table 1A-1B). Women who use supplemental feeding (formula) and those who menstruate are more likely to ovulate.

It is probably safest to resume a contraceptive in the third month following childbirth for those who breastfeed exclusively and in the third week postpartum for those who do not breastfeed or do so infrequently. A healthcare provider can help to determine the best timing and form of contraception following childbirth.

WHERE TO GET MORE INFORMATION — Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two patients are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.patients.uptodate.com). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable. National Library of Medicine

(www.nlm.nih.gov/medlineplus/healthtopics.html)
National Institute of Child Health and Human Development (NICHD)

Toll-free: (800) 370-2943
(www.nichd.nih.gov)
National Women's Health Resource Center (NWHRC)

Toll-free: (877) 986-9472
(www.healthywomen.org)
EngenderHealth

Phone: (212) 561-8000
(www.engenderhealth.org)
Planned Parenthood Federation of America

Phone: (212) 541-7800
(www.plannedparenthood.org)
The Hormone Foundation

(www.hormone.org)


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2. Fu, H, Darroch, JE, Haas, T, Ranjit, N. Contraceptive failure rates: New estimates from the 1995 National Survey of Family Growth. Fam Plann Perspect 1999; 31:56.
3. Steiner, MJ. Contraceptive effectiveness: what should the counseling message be?. JAMA 1999; 282:1405.
4. Trussell, J, Vaughan, B. Contraceptive failure, method-related discontinuation and resumption of use: results from the 1995 National Survey of Family Growth. Fam Plann Perspect 1999; 31:64.