contraception

Birth control, also known as contraception, anticonception, and fertility control, is the use of methods or devices to prevent unwanted pregnancy. Birth control has been used since ancient times, but effective and safe methods of birth control only became available in the 20th century. Planning, making available, and using birth control is called family planning. Some cultures limit or discourage access to birth control because they consider it to be morally, religiously, or politically undesirable.

The World Health Organization and United States Centers for Disease Control and Prevention provide guidance on the safety of birth control methods among women with specific medical conditions. The most effective methods of birth control are sterilization by means of vasectomy in males and tubal ligation in females, intrauterine devices (IUDs), and implantable birth control. This is followed by a number of hormone-based methods including oral pills, patches, vaginal rings, and injections. Less effective methods include physical barriers such as condoms, diaphragms and birth control sponges and fertility awareness methods. The least effective methods are spermicides and withdrawal by the male before ejaculation. Sterilization, while highly effective, is not usually reversible; all other methods are reversible, most immediately upon stopping them. Safe sex practices, such as with the use of male or female condoms, can also help prevent sexually transmitted infections. Other methods of birth control do not protect against sexually transmitted diseases. Emergency birth control can prevent pregnancy if taken within 72 to 120 hours after unprotected sex. Some argue not having sex is also a form of birth control, but abstinence-only sex education may increase teenage pregnancies if offered without birth control education, due to non-compliance.

In teenagers, pregnancies are at greater risk of poor outcomes. Comprehensive sex education and access to birth control decreases the rate of unwanted pregnancies in this age group. While all forms of birth control can generally be used by young people, long-acting reversible birth control such as implants, IUDs, or vaginal rings are more successful in reducing rates of teenage pregnancy. After the delivery of a child, a woman who is not exclusively breastfeeding may become pregnant again after as few as four to six weeks. Some methods of birth control can be started immediately following the birth, while others require a delay of up to six months. In women who are breastfeeding, progestin-only methods are preferred over combined oral birth control pills. In women who have reached menopause, it is recommended that birth control be continued for one year after the last period.

About 222 million women who want to avoid pregnancy in developing countries are not using a modern birth control method. Birth control use in developing countries has decreased the number of deaths during or around the time of pregnancy by 40% (about 270,000 deaths prevented in 2008) and could prevent 70% if the full demand for birth control were met. By lengthening the time between pregnancies, birth control can improve adult women's delivery outcomes and the survival of their children. In the developing world, women's earnings, assets, and weight, as well as their children's schooling and health, all improve with greater access to birth control. Birth control increases economic growth because of fewer dependent children, more women participating in the workforce, and less use of scarce resources.

Methods

Birth control methods include barrier methods, hormonal birth control, intrauterine devices (IUDs), sterilization, and behavioral methods. They are used before or during sex while emergency contraceptives are effective for up to five days after sex. Effectiveness is generally expressed as the percentage of women who become pregnant using a given method during the first year, and sometimes as a lifetime failure rate among methods with high effectiveness, such as tubal ligation.

The most effective methods are those that are long acting and do not require ongoing health care visits. Surgical sterilization, implantable hormones, and intrauterine devices all have first-year failure rates of less than 1%. Hormonal contraceptive pills, patches or vaginal rings, and the lactational amenorrhea method (LAM), if adhered to strictly, can also have first-year (or for LAM, first-6-month) failure rates of less than 1%. With typical use, first-year failure rates are considerably higher, at 9%, due to inconsistent use. Other methods such as condoms, diaphragms, and spermicides have higher first-year failure rates even with perfect usage. The American Academy of Pediatrics recommends long acting reversible birth control as first line for young individuals.

While all methods of birth control have some potential adverse effects, the risk is less than that of pregnancy. After stopping or removing many methods of birth control, including oral contraceptives, IUDs, implants and injections, the rate of pregnancy during the subsequent year is the same as for those who used no birth control.

For individuals with specific health problems, certain forms of birth control may require further investigations. For women who are otherwise healthy, many methods of birth control should not require a medical exam—including birth control pills, injectable or implantable birth control, and condoms. For example, a pelvic exam, breast exam, or blood test before starting birth control pills does not appear to affect outcomes. In 2009, the World Health Organization (WHO) published a detailed list of medical eligibility criteria for each type of birth control.

Hormonal

Hormonal contraception is available in a number of different forms, including oral pills, implants under the skin, injections, patches, IUDs and a vaginal ring. They are currently available only for women, although hormonal contraceptives for men have been and are being clinically tested. There are two types of oral birth control pills, the combined oral contraceptive pills (which contain both estrogen and a progestin) and the progestogen-only pills (sometimes called minipills). If either is taken during pregnancy, they do not increase the risk of miscarriage nor cause birth defects. Both types of birth control pills prevent fertilization mainly by inhibiting ovulation and thickening cervical mucus. They may also change the lining of the uterus and thus decrease implantation. Their effectiveness depends on the user's adherence to taking the pills.

Combined hormonal contraceptives are associated with a slightly increased risk of venous and arterial blood clots. Venous clots, on average, increase from 2.8 to 9.8 per 10,000 women years which is still less than that associated with pregnancy. Due to this risk, they are not recommended in women over 35 years of age who continue to smoke. Due to the increased risk, they are included in decision tools such as the DASH score and PERC rule used to predict the risk of blood clots.

The effect on sexual drive is varied, with increase or decrease in some but with no effect in most. Combined oral contraceptives reduce the risk of ovarian cancer and endometrial cancer and do not change the risk of breast cancer. They often reduce menstrual bleeding and painful menstruation cramps. The lower doses of estrogen released from the vaginal ring may reduce the risk of breast tenderness, nausea, and headache associated with higher dose estrogen products.

Progestin-only pills, injections and intrauterine devices are not associated with an increased risk of blood clots and may be used by women with a history of blood clots in their veins. In those with a history of arterial blood clots, non-hormonal birth control or a progestin-only method other than the injectable version should be used. Progestin-only pills may improve menstrual symptoms and can be used by breastfeeding women as they do not affect milk production. Irregular bleeding may occur with progestin-only methods, with some users reporting no periods. The progestins drospirenone and desogestrel minimize the androgenic side effects but increase the risks of blood clots and are thus not first line. The perfect use first-year failure rate of injectable progestin is 0.2%; the typical use first failure rate is 6%.

File:Plaquettes de pilule.jpg, alt=birth control pill packages, Three varieties of birth control pills in calendar oriented packaging
File:Birth Control Pills.png, Birth control pills
File:BirthControlPatch.JPG, alt=a contraceptive patch, A transdermal contraceptive patch
File:NuvaRing in hand.jpg, alt=a vaginal ring, A NuvaRing vaginal ring

Barrier

Barrier contraceptives are devices that attempt to prevent pregnancy by physically preventing sperm from entering the uterus. They include male condoms, female condoms, cervical caps, diaphragms, and contraceptive sponges with spermicide.

Globally, condoms are the most common method of birth control. Male condoms are put on a man's erect penis and physically block ejaculated sperm from entering the body of a sexual partner. Modern condoms are most often made from latex, but some are made from other materials such as polyurethane, or lamb's intestine. Female condoms are also available, most often made of nitrile, latex or polyurethane. Male condoms have the advantage of being inexpensive, easy to use, and have few adverse effects. Making condoms available to teenagers does not appear to affect the age of onset of sexual activity or its frequency. In Japan, about 80% of couples who are using birth control use condoms, while in Germany this number is about 25%, and in the United States it is 18%.

Male condoms and the diaphragm with spermicide have typical use first-year failure rates of 18% and 12%, respectively. With perfect use condoms are more effective with a 2% first-year failure rate versus a 6% first-year rate with the diaphragm. Condoms have the additional benefit of helping to prevent the spread of some sexually transmitted infections such as HIV/AIDS, however, condoms made from animal intestine do not.

Contraceptive sponges combine a barrier with a spermicide. Like diaphragms, they are inserted vaginally before intercourse and must be placed over the cervix to be effective. Typical failure rates during the first year depend on whether or not a woman has previously given birth, being 24% in those who have and 12% in those who have not. The sponge can be inserted up to 24 hours before intercourse and must be left in place for at least six hours afterward. Allergic reactions and more severe adverse effects such as toxic shock syndrome have been reported.

File:Kondom.jpg, A rolled up male condom.
File:Condom unrolled durex.jpg, alt=an unrolled condom, An unrolled male latex condom
File:Préservatif féminin.jpg, alt=a female condom, A polyurethane female condom
File:Contraceptive diaphragm.jpg, alt=a diaphragm, A diaphragm vaginal-cervical barrier, in its case with a quarter U.S. coin.
File:Éponge spermicide.jpg, alt=a contraceptive sponge, A contraceptive sponge set inside its open package.

Intrauterine devices

The current intrauterine devices (IUD) are small devices, often 'T'-shaped, containing either copper or levonorgestrel, which are inserted into the uterus. They are one form of long-acting reversible contraception which are the most effective types of reversible birth control. Failure rates with the copper IUD is about 0.8% while the levonorgestrel IUD has a failure rates of 0.2% in the first year of use. Among types of birth control, they, along with birth control implants, result in the greatest satisfaction among users. As of 2007, IUDs are the most widely used form of reversible contraception, with more than 180 million users worldwide.

Evidence supports effectiveness and safety in adolescents and those who have and have not previously had children. IUDs do not affect breastfeeding and can be inserted immediately after delivery. They may also be used immediately after an abortion. Once removed, even after long term use, fertility returns to normal immediately.

While copper IUDs may increase menstrual bleeding and result in more painful cramps, hormonal IUDs may reduce menstrual bleeding or stop menstruation altogether. Cramping can be treated with painkillers like non-steroidal anti-inflammatory drugs. Other potential complications include expulsion (2–5%) and rarely perforation of the uterus (less than 0.7%). A previous model of the intrauterine device (the Dalkon shield) was associated with an increased risk of pelvic inflammatory disease, however the risk is not affected with current models in those without sexually transmitted infections around the time of insertion. IUDs appear to decrease the risk of ovarian cancer.

Sterilization

Surgical sterilization is available in the form of tubal ligation for women and vasectomy for men. Tubal ligation decreases the risk of ovarian cancer. Short term complications are twenty times less likely from a vasectomy than a tubal ligation. After a vasectomy, there may be swelling and pain of the scrotum which usually resolves in one or two weeks. Chronic scrotal pain associated with negative impact on quality of life occurs after vasectomy in about 1-2% of men. With tubal ligation, complications occur in 1 to 2 percent of procedures with serious complications usually due to the anesthesia. Neither method offers protection from sexually transmitted infections. Sometimes, salpingectomy is also used for sterilization in women.

This decision may cause regret in some men and women. Of women who have undergone tubal ligation after the age of 30, about 6% regret their decision, as compared with 20-24% of women who received sterilization within one year of delivery and before turning 30, and 6% in nulliparous women sterilized before the age of 30. By contrast, less than 5% of men are likely to regret sterilization. Men who are more likely to regret sterilization are younger, have young or no children, or have an unstable marriage. In a survey of biological parents, 9% stated they would not have had children if they were able to do it over again.

Although sterilization is considered a permanent procedure, it is possible to attempt a tubal reversal to reconnect the fallopian tubes or a vasectomy reversal to reconnect the vasa deferentia. In women, the desire for a reversal is often associated with a change in spouse. Pregnancy success rates after tubal reversal are between 31 and 88 percent, with complications including an increased risk of ectopic pregnancy. The number of males who request reversal is between 2 and 6 percent. Rates of success in fathering another child after reversal are between 38 and 84 percent; with success being lower the longer the time period between the vasectomy and the reversal. Sperm extraction followed by in vitro fertilization may also be an option in men.

Behavioral

Behavioral methods involve regulating the timing or method of intercourse to prevent introduction of sperm into the female reproductive tract, either altogether or when an egg may be present. If used perfectly the first-year failure rate may be around 3.4%, however if used poorly first-year failure rates may approach 85%.

Fertility awareness

Fertility awareness methods involve determining the most fertile days of the menstrual cycle and avoiding unprotected intercourse. Techniques for determining fertility include monitoring basal body temperature, cervical secretions, or the day of the cycle. They have typical first-year failure rates of 24%; perfect use first-year failure rates depend on which method is used and range from 0.4% to 5%. The evidence on which these estimates are based, however, is poor as the majority of people in trials stop their use early. Globally, they are used by about 3.6% of couples. If based on both basal body temperature and another primary sign, the method is referred to as symptothermal. First-year failure rates of 20% overall and 0.4% for perfect use have been reported in clinical studies of the symptothermal method. A number of fertility tracking apps are available, as of 2016, but they are more commonly designed to assist those trying to get pregnant rather than prevent pregnancy.

Withdrawal

The withdrawal method (also known as coitus interruptus) is the practice of ending intercourse ("pulling out") before ejaculation. The main risk of the withdrawal method is that the man may not perform the maneuver correctly or in a timely manner. First-year failure rates vary from 4% with perfect usage to 22% with typical usage. It is not considered birth control by some medical professionals.

There is little data regarding the sperm content of pre-ejaculatory fluid. While some tentative research did not find sperm, one trial found sperm present in 10 out of 27 volunteers. The withdrawal method is used as birth control by about 3% of couples.

Abstinence

Sexual abstinence may be used as a form of birth control, meaning either not engaging in any type of sexual activity, or specifically not engaging in vaginal intercourse, while engaging in other forms of non-vaginal sex. Complete sexual abstinence is 100% effective in preventing pregnancy. However, among those who take a pledge to abstain from premarital sex, as many as 88% who engage in sex, do so prior to marriage. The choice to abstain from sex cannot protect against pregnancy as a result of rape, and public health efforts emphasizing abstinence to reduce unwanted pregnancy may have limited effectiveness, especially in developing countries and among disadvantaged groups.

Deliberate non-penetrative sex without vaginal sex or deliberate oral sex without vaginal sex are also sometimes considered birth control. While this generally avoids pregnancy, pregnancy can still occur with intercrural sex and other forms of penis-near-vagina sex (genital rubbing, and the penis exiting from anal intercourse) where sperm can be deposited near the entrance to the vagina and can travel along the vagina's lubricating fluids.

Abstinence-only sex education does not reduce teenage pregnancy. Teen pregnancy rates and STI rates are generally the same or higher in states where students are given abstinence-only education, as compared with comprehensive sex education. Some authorities recommend that those using abstinence as a primary method have backup methods available (such as condoms or emergency contraceptive pills).

Lactation

The lactational amenorrhea method involves the use of a woman's natural postpartum infertility which occurs after delivery and may be extended by breastfeeding. This usually requires the presence of no periods, exclusively breastfeeding the infant, and a child younger than six months. The World Health Organization states that if breastfeeding is the infant's only source of nutrition, the failure rate is 2% in the six months following delivery. Six uncontrolled studies of lactational amenorrhea method users found failure rates at 6 months postpartum between 0% and 7.5%. Failure rates increase to 4–7% at one year and 13% at two years. Feeding formula, pumping instead of nursing, the use of a pacifier, and feeding solids all increase its failure rate. In those who are exclusively breastfeeding, about 10% begin having periods before three months and 20% before six months. In those who are not breastfeeding, fertility may return four weeks after delivery.

Emergency

Emergency contraceptive methods are medications (sometimes misleadingly referred to as "morning-after pills") or devices used after unprotected sexual intercourse with the hope of preventing pregnancy. Emergency contraceptives are often given to victims of rape. They work primarily by preventing ovulation or fertilization. They are unlikely to affect implantation, but this has not been completely excluded. A number of options exist, including high dose birth control pills, levonorgestrel, mifepristone, ulipristal and IUDs. Providing emergency contraceptive pills to women in advance does not affect rates of sexually transmitted infections, condom use, pregnancy rates, or sexual risk-taking behavior. All methods have minimal side effects.

Levonorgestrel pills, when used within 3 days, decrease the chance of pregnancy after a single episode of unprotected sex or condom failure by 70% (resulting in a pregnancy rate of 2.2%). Ulipristal, when used within 5 days, decreases the chance of pregnancy by about 85% (pregnancy rate 1.4%) and is more effective than levonorgestrel. Mifepristone is also more effective than levonorgestrel, while copper IUDs are the most effective method. IUDs can be inserted up to five days after intercourse and prevent about 99% of pregnancies after an episode of unprotected sex (pregnancy rate of 0.1 to 0.2%). This makes them the most effective form of emergency contraceptive. In those who are overweight or obese, levonorgestrel is less effective and an IUD or ulipristal is recommended.

Dual protection

Dual protection is the use of methods that prevent both sexually transmitted infections and pregnancy. This can be with condoms either alone or along with another birth control method or by the avoidance of penetrative sex.

If pregnancy is a high concern, using two methods at the same time is reasonable. For example, two forms of birth control are recommended in those taking the anti- acne drug isotretinoin or anti-epileptic drugs like carbamazepine, due to the high risk of birth defects if taken during pregnancy.

Effects

Health

Contraceptive use in developing countries is estimated to have decreased the number of maternal deaths by 40% (about 270,000 deaths prevented in 2008) and could prevent 70% of deaths if the full demand for birth control were met. These benefits are achieved by reducing the number of unplanned pregnancies that subsequently result in unsafe abortions and by preventing pregnancies in those at high risk.

Birth control also improves child survival in the developing world by lengthening the time between pregnancies. In this population, outcomes are worse when a mother gets pregnant within eighteen months of a previous delivery. Delaying another pregnancy after a miscarriage however does not appear to alter risk and women are advised to attempt pregnancy in this situation whenever they are ready.

Teenage pregnancies, especially among younger teens, are at greater risk of adverse outcomes including early birth, low birth weight, and death of the infant. In 2012 in the United States 82% of pregnancies in those between the ages of 15 to 19 years old are unplanned. Comprehensive sex education and access to birth control are effective in decreasing pregnancy rates in this age group.

Birth control methods, especially hormonal methods, can also have undesirable side effects. Intensity of side effects can range from minor to debilitating, and varies with individual experiences. These most commonly include change in menstruation regularity and flow, nausea, breast tenderness, headaches,  weight gain, and mood changes (speci