Contraception refers to preventing conception, the process by which a sperm from a fertile male joins with an ovum (egg) of a fertile female during vaginal sexual intercourse. Any fertile female who has vaginal intercourse without contraception with a fertile male may become pregnant. If a couple prefers not to conceive a child, then the use of contraception or “birth control” is advised.
There are many forms of contraception: (1) “natural” methods, to avoid vaginal intercourse or to time intercourse so that it does not occur during the days in each menstrual cycle when a woman is most fertile; (2) chemical methods, to inactivate sperm; (3) barrier methods, to prevent the male sperm from reaching the female egg; (4) hormonal methods, to alter the process of ovulation (release of the female egg) or other biological conditions necessary for conception; (5) use of intrauterine devices, to influence the condition of the uterine lining; and (6) surgical methods, to prevent the release or availability of sperm or eggs. Each contraceptive method has its own advantages and disadvantages.
Abstinence and other nonpenetrative sexual behaviors are 100 percent effective ways to avoid unintended conception. Abstinence involves no sexual contact, whereas nonpenetrative sexual behavior refers to activities such as mutual masturbation (sexual touching that can lead to orgasm). Oral and anal sex also avoid conception but these penetrative activities may lead to sexually transmitted infections (STIs) such as HIV, chlamydia, and gonorrhea.
Natural methods can also be used in conjunction with vaginal intercourse. The withdrawal method, also known as coitus interruptus, requires that the man withdraw his penis from his partners vagina prior to ejaculation (the release of semen during orgasm). Although commonly practiced, especially among adolescents, withdrawal has a relatively high (24 percent) failure rate because it can be difficult for a man to withdraw in time and because there are fluids that escape the penis prior to ejaculation that may contain viable sperm.
Natural family planning methods are based on the idea that fertilization is most likely to occur around the time of ovulation, and that by avoiding intercourse during those times, conception is less likely to occur. These are several ways to determine the time of ovulation, including the basal body temperature approach (use of a woman’s daily morning temperature), the cervical mucus method (careful monitoring of vaginal wetness), and the calendar method (tracking menstrual cycles carefully). Overall, failure rates tend to be relatively high (21 percent) for these methods because they require very careful and accurate monitoring as well as discipline to avoid intercourse during ovulation. However, they have no side effects, are inexpensive, and enjoy greater acceptability among some religious traditions.
The lactational amenorrhea method is available only to women who are nursing, and involves the use of breastfeeding to suppress ovulation. This method is effective only when (1) the infant is less than 6 months old, (2) the mother’s menses has not returned, and (3) a nursing mother breastfeeds for almost all feedings.
Spermacides such as nonoxynol-9 and octoxynol-9 are chemicals placed in the vagina just prior to intercourse to inactivate sperm. They are available without a prescription, and can be used easily by a woman without her partner’s knowledge; they are available in the form of cream, foam, gels, suppositories, and film. When spermacides are used by themselves (without a barrier), they have a failure rate of 26 percent. However, recent research suggests that use of spermacides may irritate the lining of the vagina and increase the likelihood of HIV transmission if a woman’s partner is infected.
Male condoms or “rubbers” refer to a sheath (covering) that is worn over the penis during intercourse. Condoms are made from latex (rubber), polyurethane (plastic), or lamb intestines (“lambskin”). To be effective, condoms must be applied correctly prior to intromission (insertion of the penis into the vagina) and not removed until the man has withdrawn his penis from his partner’s vagina. The estimated failure rate for condoms is 14 percent. A major advantage of the male latex (and polyurethane) condom is that it also protects against HIV and many other STIs.
The diaphragm is a flexible rubber disk with a rigid rim that is used with a spermacide; it is inserted into the vagina by a woman prior to intercourse and must be left in place for a minimum of 6 hr after intercourse. The cervical cap is a dome-shaped rubber cap that is inserted into the vagina by a woman prior to intercourse; it can be left in place for up to 48 hr. Both the diaphragm and the cervical cap must be fitted by a health professional, are used with a spermacide, and have a failure rate of 12 percent.
The contraceptive sponge is made of polyurethane, used with a spermacide, and inserted into the vagina prior to intercourse. It is available without a prescription, is easy to use, and can be left in place for up to 24 hr; however, it has a failure rate of 18-28 percent.
The most recent female barrier method to be developed is the female condom, which consists of a lubricated polyurethane sheath with a flexible ring on each end; one end is inserted into the vagina and the other remains outside; thus, the female condom is visible to the partner. The failure rate is estimated at 21-26 percent; like the male latex condom, the female condom protects against HIV and other STIs.
The use of progestin only or estrogen and progestin together is common. These hormones are taken well in advance of vaginal intercourse and may be administered by mouth (i.e., the pill), by an injection (e.g., Depo-Provera), or implanted under the skin (e.g., Norplant). The implants and injectables have the lowest failure rates (2-3 percent), followed by the pill (8 percent). For some women, use of the estrogen and progestin combination also provides additional health benefits including protection against some cancers and pelvic inflammatory disease (PID). For other women, especially those who smoke or who have a history of cardiovascular difficulties, the use of such hormones can have serious side effects. Although very effective, the use of steroids requires careful medical supervision.
Intrauterine devices (IUDs) are small, plastic, and flexible devices that are inserted into the uterus though the cervix by a trained health professional well in advance of intercourse. IUDs alter uterine and tubal fluids and inhibit the movement of sperm through the cervical mucus and uterus. IUDs have a 4-5 percent failure rate and carry a small risk of PID among some women.
Vasectomy is an operation to cut or tie off the tube (the vas deferens) that sperm use to travel from the testicles to the penis. Tubal ligation involves surgery to close the fallopian tubes, making it impossible for sperm and egg to unite. Both surgical procedures have an extremely low failure rate (<1 percent) but they are usually irreversible; thus, these procedures tend to be used by adults who have already had, or do not wish to have, children. Also, tubal ligation is a complex medical procedure that leads to complications in 2 percent of cases.
Combining Contraception and Disease Prevention
Most contraceptive methods do not protect against HIV and other STIs. Of the methods discussed, only abstinence, nonpenetrative sexual behaviors, and latex and polyurethane male and female condoms prevent both conception and STI transmission. Sexually active couples are advised to seek testing (provided by most health departments) prior to sexual activity to be sure that neither partner is infected with a STI. Testing for STIs is important because a person can have an STI without any symptoms. After test results confirm that both partners are “negative” (i.e., not infected), then the contraceptive methods described can be used within the context of a mutually monogamous relationship (both partners agree to have no other relationships or sexual partners) without fear of acquiring an STI. If there is any doubt about the commitment of either partner, then continued use of a male or female condom is advised.
Factors That Predict Contraceptive Use
Unintended pregnancies occur commonly in the United States due to nonuse or incorrect use of contraceptive methods. In the United States, approximately 60 percent of all pregnancies (86 percent of all pregnancies among unmarried adolescents) are unintended.
Contraceptive use is associated with a wide range of psychosocial and economic factors, including knowledge about contraception and reproductive health, skill in using contraceptives properly, the quality of a couple’s relationship, access to reproductive health services and contraceptives, personal and cultural comfort with sexuality, religious and political preferences, and media influences. Ongoing research seeks to increase current understanding of the causes of contraceptive use and nonuse and to identify educational, psychological, medical, and public health programs that can promote contraceptive use among persons who choose to be sexually active.